Этика, Часть V, Теорема 28

This proposition is self--evident. For whatsoever we understand clearly and distinctly, we understand either through itself, or through that which is conceived through itself; that is, ideas which are clear and distinct in us, or which are referred to the third kind of knowledge (II. xl. note. ii.) cannot follow from ideas that are fragmentary and confused, and are referred to knowledge of the first kind, but must follow from adequate ideas, or ideas of the second and third kind of knowledge; therefore (Def. of the Emotions, i.), the desire of knowing things by the third kind of knowledge cannot arise from the first, but from the second kind. Q.E.D.