In Definition 3 of Part III of the Ethics Spinoza writes, “By emotion (affectus) I mean the modifications of the body, whereby the active power of the said body is increased or diminished, aided or constrained, and also the ideas of such modifications. N.B. If we can be the adequate cause of any of these modifications, I then call the emotion an activity, otherwise I call it a passion, or state wherein the mind is passive.” This is an extraordinary and remarkable definition of emotion, that goes well beyond associations we might have between emotions and feelings.
From the outset it can be discerned that the definition has two parts. On the one hand, affectus refers to modifications of the body. Insofar as Spinoza references the active power of the body, we should not understand feelings, but rather the capacity of the body to act and be acted upon. 
Thus, for example, the affects of a bat consist, on the one hand, in its capacity to encounter the world in terms of sonar, but also in its ability to fly, grasp, tear with its teeth, etc. Likewise, my fingers pounding away on this keyboard constitute an affect or capacity of my body. Or rather, my body here enters into an assemblage of affects produced through the conjunction– the “and” –of my hands and the key board, the two acting upon one another and being acted upon by one another. Through this conjugation of affects the power of bodies, according to Spinoza, is either enhanced or diminished, checked or assisted.
For this reason, Spinoza will write, in a beautiful passage, that “…nobody as yet has determined the limits of the body’s capabilities: that is, nobody as yet has learned from experience what the body can and cannot do…” (Prop 2, Scholium, Part III). It is notable that Spinoza here uses the indefinite article, indicating that bodies aren’t to be restricted to human or living bodies, but to all bodies. If, then, no one knows what a body can do, this is because the assemblages into which bodies can enter are limitless. 
And in entering into an assemblage or a network, the body’s about of acting is increased or diminished, assisted or checked. We can thus think of a body as being akin to a field of potentials, such that in entering into an assemblage with another body, potentials of the body are drawn forth or pulled forth from the body, manifesting themselves for the very first time. Already we can sense that Spinoza’s entire theory of the emotions is contained in this conception of the body as a power of acting and being acted upon. As Spinoza will say, emotions are also composed of the ideas that accompany these affects (thoughts, feelings). Those assemblages that enhance a body’s power of acting will be accompanied by joyous ideas of these affections, while those that diminish the body’s power of acting will be accompanied by sad ideas of these affections.
In a recent National Public Radio story it was reported that ideas of affects are themselves contagious between bodies:
A new study by researchers at Harvard University and the University of California, San Diego documents how happiness spreads through social networks.
They found that when a person becomes happy, a friend living close by has a 25 percent higher chance of becoming happy themselves. A spouse experiences an 8 percent increased chance and for next-door neighbors, it’s 34 percent.
“Everyday interactions we have with other people are definitely contagious, in terms of happiness,” says Nicholas Christakis, a professor at Harvard Medical School and an author of the study.
Perhaps more surprising, Christakis says, is that the effect extends beyond the people we come into contact with. When one person becomes happy, the social network effect can spread up to 3 degrees — reaching friends of friends.
It would thus appear that emotions, far from being internal, private affairs, but are the result of collective assemblages where my own happiness is dependent on the happiness of those about me. But what, we might ask, is going on at the level of affects, what is going on at the level of bodily assemblages, to produce these ideas of affections accompany these affections?
Larval Subjects . 
December 5, 2008 at 8:21 pm
This IS an extraordinary concept that Spinoza has come up with, so full of potentiating analysis. The entire human world (at least one can say the human world) expands with possibilities for combination and re-combination, under the auspices of a rather elementary Joy/Sadness dichotomy, a dichotomy so simple that anyone can understand it.
I would only add to your intitial citation, the qualification of Being Spinoza provides in the General Defintion of the Affects at the end of Part III. For others less familiar than you, this is where Spinoza’s specific defintion gains its full, ontological (if problematic), force. Each affect, that is each passing into a more Joyous, or more Sad state, is an ontological shift in a degree of Being:
“…But it should be noted that, when I say ‘a greater or lesser force of existing than before’, I do not understand that the Mind compares its Body’s present constitution with a past constitution, but that the idea which constitutes the form of the affect affirms of the body something which really involves more or less reality than before”
When we are Joyful, however mistakenly so, we literally acquire more Being, asymptotically related to that which has the greatest Being, self-causing Substance.
LS: “It would thus appear that emotions, far from being internal, private affairs, but are the result of collective assemblages where my own happiness is dependent on the happiness of those about me. But what, we might ask, is going on at the level of affects, what is going on at the level of bodily assemblages, to produce these ideas of affections accompany these affections?”
Kvond: I don’t know if these are rhetorical or open questions, but in Spinoza it seems that there are two things which are going on. Either we are increasing our capacity to act (and our degree of Being), through imaginary processes which Spinoza finds to be governed by the “imitation of the affects”:
“If we imagine a thing like us, toward which we have had no affect, to be affected with some affect, we are thereby affected with a like affect” (EIIIp27)
and thus through the imagination assembling trans-personal bodies. Or, we are rationally acquiring more adequate ideas, thereby through our knowledge of causes, becoming more our own cause (it is unclear if one can increase one’s power of acting without also increasing the adequacy of one’s ideas, since the parallel postulate requires mutal increase).
What is so interesting about this treatment of affects is that: The more empowered one person becomes, the less a “person” that person is (the whole of its causal relations, animate and inanimate, human and inhuman all get swept up in the expression of that power). Power only manifests itself trans-personally.
As to the supposed privacy of emotions and feelings, Wittgenstein has a thought related to Spinoza’s imitation of affects:
Look at a stone and imagine it having sensations.-One says to oneself: How could one so much as get the idea of ascribing a sensation to a thing?…And now look at a wriggling fly and at once these difficulties vanish and pain seems to get a foothold here…(PI 284)
December 6, 2008 at 2:24 pm
Dr Sinthome, I think Kvond deserves an A+ for being the most prodigious student in the class! His contributions are not only elaborate but also quite piercing. Speaking of which, I noticed that in your online student assessment you only got a 4 for the hotness factor? I would have given you a straight 10.
As regards networked emotions, I noticed in the past decade an increase in group events. Especially in the rhythm and blues culture you see amongst the youth, people tend to congregate into these group dance orgies. This is supposed to provide some kind of an affective rush I guess.
December 6, 2008 at 4:32 pm
http://parodycentrum.wordpress.com/2008/12/06/scenes-from-the-classroom/
December 7, 2008 at 7:12 pm
Dr. Sinthome, we must resolutely set aside Parodycenter’s puerile attempts at reducing every interaction to a power struggle, even while acknowledging his uncanny ability to give voice to the unconscious…
I understand that the empirical study of networked emotion you cite holds a position of secondary importance in your post. With no intent of distracting you from your larger purpose, I note some interesting details presented in online summaries of this study. The “happiness infection” was apparently more virulently transmitted among strangers and neighbors than between spouses. Though I’m not sure I’d have predicted it, I can see why this might be: interpersonal history and mutual expectations get in the way of emotional flow. It also turns out that happiness didn’t flow through the network of co-workers — maybe it reflects the alienation of late-modern capitalism. Unhappiness wasn’t as infective as happiness: the correlation was there, but smaller in magnitude. The researchers speculated that happiness brings people together whereas unhappiness separates them. This speculation is enhanced by the researchers’ finding that those individuals positioned at the centers of social networks seemed to benefit most from the infectious spread of happiness while remaining relatively unaffected by unhappiness intruding from the periphery of the network. Other researchers have demonstrated that these network effects are often halved when controlled statistically for the usual sociodemographic covariates: sex, age, race, education, maternal education, family income. I don’t know whether the results of the happiness study have been subjected to these sorts of covariate analysis.
December 7, 2008 at 8:52 pm
interpersonal history and mutual expectations get in the way of emotional flow. It also turns out that happiness didn’t flow through the network of co-workers — maybe it reflects the alienation of late-modern capitalism.
Clysmatics you didn’t complete the clysmalysis at all since your variables aren’t properly operationalized. Happiness doesn’t have to equal being elated or in an ecstasy, it can also be a feeling of contentedness. And the contagion doesn’t have to spread in dramatic ways; it can also be a quiet fart under the blanket, the so-called Dutch oven, making your spouse unhappy.
I remember mentioning in relation to the Zack Snyder debates, specifically DAWN OF THE DEAD, that the zombie contagion – infestation referred to chaotic mass spectacles e.g. 9-11 – which dr. Zizek views as a dekline of simbolik efikasy. The question arises, how does Spinoza cf Deleuze view the issue of channeling this spontaneous, contagious force?
December 7, 2008 at 9:01 pm
Dejan, Spinoza argues that the body strives to combine or form assemblages with those beings that enhance its power of acting, so these assemblages spread through conjugations of bodies as I argued in the post. From a psychoanalytic perspective, I think this thesis is particularly valuable as it brings into relief just how mysterious the death drive or compulsion repetition is, allowing us to see just why phenomena such as the compulsion to repeat are genuine metapsychological issues. Early Freud, of course, thinks very much in terms of a Spinozist model, seeing the subject as essentially pleasure or power seeking and symptoms as a product of the repression of some drive dimension of pleasure. When Freud discovers the repetition of traumatic experiences, he has to significantly revise his model. There is something right about what Spinoza is saying in his theory of affects, but like all epicurean models of desire, it runs afoul of questions of lethal repetition and jouissance.
December 7, 2008 at 9:08 pm
Yes but what is the motivation for the being to seek an enhancement of the power of its acting, dr. Sinthome; this is unclear. Does Spinoza explain this in rationalist terms, does the being seek balance and harmony, optimal conditions, or is there some utilitarian motive etc. What is the regulating mechanism, how do the networks come into a functional position so that the world doesn’t fall apart.
December 7, 2008 at 10:20 pm
Spinoza presents the principle behind this in Proposition 6-8 of Part 3 of the Ethics:
http://frank.mtsu.edu/~rbombard/RB/Spinoza/ethica3.html#Prop.%20VI.
December 7, 2008 at 11:04 pm
Thank you dr. Sinthome, this is a very helpful reference; I shall endeavor to return with an essay – by tomorrow.
December 8, 2008 at 1:11 am
dr . Sinthome you don’t have to publish this one
I understand that the empirical study of networked emotion you cite holds a position of secondary importance in your post. With no intent of distracting you from your larger purpose, I note some interesting details presented in online summaries of this study.
With no hope of being able to suck your Lacanian prowess, I shall contend myself with slithering in the vicinity of your feet
December 8, 2008 at 4:25 am
Is Parodycenter spreading his own unhappiness virally, or is he making himself happy at others’ expense? To shed light on this question we must conduct a series of experiments, preferably one involving the attachment of electrodes to sensitive body parts.
December 9, 2008 at 12:44 am
LS: “From a psychoanalytic perspective, I think this thesis is particularly valuable as it brings into relief just how mysterious the death drive or compulsion repetition is, allowing us to see just why phenomena such as the compulsion to repeat are genuine metapsychological issues”.
Kvond: You touch on the problem of this kind of interpretation when you say later that a Spinozist account does not take up lethal repetition, but the divergence between Spinoza and Freud on this is not just one of degree, but of category. Freud took up the Death Drive to explain compulsive acts which fell outside of the Pleasure Principle. This is absolutely metaphysically impossible for Spinoza. Freud sets up an entirely different “motivation” so to speak, whereas for Spinoza EVERYTHING falls under the Pleasure Principle. For instance, suicide is for Spinoza a metaphysically impossible act (it violates the very relationship which constitutes what an act IS).
A short note on Spinoza and suicide:
http://kvond.wordpress.com/2008/11/14/spinoza-on-suicide-the-break-between-the-imagination-and-the-body/
While I think we can agree that Freud was influenced by Spinoza, I am unsure that would could count his division between Pleasure and Death, Organic and Inorganic, as one of them (at least in any direct way).
December 9, 2008 at 2:10 am
Right Kvond, this was my point re: Freud and Spinoza. Of course, it’s necessary to distinguish between the compulsion to repeat (what I refer to as the Death Drive)and Freud’s theory of the Death Drive or compulsion to repeat. For me the verdict is still out on just how the Death Drive or the compulsion to repeat is to be explained in metapsychological terms, though Freud’s account is not, in my view, a plausible candidate. Lacan fares much better. Spinoza is of value in bringing out the strangeness of the compulsion to repeat precisely because his largely epicurean theory of the affects. As a phenomenon the death drive at least appears to be deeply at odds with this understanding of the human mind and body. Freud was similarly perplexed when he came across this phenomenon. I am less interested in what might or might not conflict with Spinoza’s metaphysics as I myself am not an advocate of that metaphysics, though I am certainly indebted to a number of his concepts. I pick up concepts from Spinoza, as I do from a number of other philosophers, in much the same way that a bricoleur proceeds… Picking up whatever is available at hand to articulate what I’m trying to work through without being very interested in embracing any of the various systems from which these elements might be drawn.
December 9, 2008 at 2:41 am
LS: “I am less interested in what might or might not conflict with Spinoza’s metaphysics as I myself am not an advocate of that metaphysics, though I am certainly indebted to a number of his concepts.”
Kvond: I only posted for the benefit of any of your readers who may not have been able to discern the severity of departure of Freud from Spinoza on this matter, as you only subtly pointed out a tension between them. Though you personally might not find the issue of a conflict between the two thinkers of any interest, if the two thinkers are going to be put into communication with each other in a “metapsychological” way (as you suggest they can be), in my view the metaphysical impossibility of the Freudian Death Drive (as he structured it) from a Spinozist point of view, needs to be noted.
Actually, I find in the Freudian compulsion to repeat something very inherent in Spinoza’s conatus directives. Compulsions to repeat, far from a desire toward Death, might be better seen as attempts to solidify body boundries under conceptions of dissolution (the perceived threat thereof). One repeats in order to sew closed what is felt to be too open (at least that is my sense). I don’t really see this as a Thanatos/Eros division. But perhaps this is because from a Spinoza conception, Thanatos (the inorganic) is shot through with Eros (all is organic). The Ultimate Dead Thing, Substance, Is the Most Active, Expressive thing that there is.
And in no way do I judge your pleasure in taking ideas and concepts wherever you see fit to find them. Again, I comment on a larger picture, that which places Freud in juxtaposition to Spinoza on the issue of drives.
December 23, 2008 at 7:02 pm
[…] screen, in relation to both affect and emotion, may have some resonances with Levi’s recent post on […]