I
Desire
The essence of the mind is composed of adequate and inadequate ideas (as we have shown), and therefore both in so far as it has the former and in so far as it has the latter, it endeavors to persevere in its being, and endeavors to persevere in it for an indefinite time. But since the mind, through the ideas of the modifications of the body, is necessarily conscious of itself, it is therefore conscious of its effort.
This effort, when it is related to the mind alone, is called will, but when it is related at the same time both to the mind and the body, is called appetite, which is therefore nothing but the very essence of man, from the nature of which necessarily follow those things which promote his preservation, and thus he is determined to do those things. Hence there is no difference between appetite and desire, unless in this particular, that desire is generally related to men in so far as they are conscious of their appetites, and it may therefore be defined as appetite of which we are conscious. From what has been said it is plain, therefore, that we neither strive for, wish, seek, nor desire anything because we think it to be good, but, on the contrary, we adjudge a thing to be good because we strive for, wish, seek, or desire it.