This paper starts from the premise that Spinoza and Hume share a realisticnaturalistic approach to human nature. Human beings are finite parts of nature, and as such strongly interdependent creatures. This interdependence is reflected in the central social-psychological principles that Hume and Spinoza employ, respectively sympathy and affectuum imitatio. Both principles show the immediacy of the ... [Show full abstract] communication of passions, and the strong influence that other people's passions exert over our own affective lives. Central to this paper are an analysis and comparison of the working of sympathy and imitation of affects. As it turns out, both philosophers consider humans to be limitedly social beings. Social, because we tend to be moved by the pains and pleasures of our fellows. Limitedly social, because our egoistic side limits the scope of our fellow-feeling, and may turn the other's pain into our pleasure and vice versa. This puts a pressure on (larger) groups; their living together can never be truly harmonious without external interference. Spinoza and Hume, therefore, regard a further stabilisation and harmonisation of collective affective life as a key political concern. As will finally be argued, the precise way in which this concern is fleshed out in their political theories makes them occupy a shared, distinctive position in early modern political thought.