Human minds are modes of thought, and the question of what they understand and how is an important one. But answering that question does not fully capture what Spinoza calls the ‘actual essence’ of finite beings, which is their striving. The striving of a human being to persevere in its being, to increase its power to think and to act, to produce the effects that follow from its nature, insofar as it is expressed both corporeally and mentally – Spinoza calls this desire. What does the persistence of inadequate ideas, and so of unconscious dimensions of thought in even the most active mind, mean for this conception of desire as the actual essence of individual human beings?

In the previous chapter, I argued that Spinoza's categorical framework of adequate and inadequate ideas, which is designed to respond to the ethical problematic that informs his metaphysics, namely the increase of power, has the following significant characteristics. First, the adequate and inadequate are not related to one another as are the true to the false. The inadequate is characterised not by anything positive on account of which it could be called false, but rather by its partiality: an inadequate idea does not fully explain that of which it is an idea, but clearly and distinctly expresses only some part or aspect of it. Inadequate ideas do not express their own causes clearly and distinctly, but they must nevertheless involve these causes, and thus do so only obscurely and indistinctly. Error consists, then, in taking an inadequate idea to be adequate, that is, in confusing the partial for the completely expressive.

Second, following Spinoza's analyses in Propositions 24 to 31 of Part II, there are some things of which we can only form inadequate ideas. In particular, as we saw, the human mind can only form inadequate ideas of the natures of external bodies and the parts of its own bodies, the nature of its own mind based on the ideas of its body's affections, and the durations of singular things, which includes itself as well as things outside it.