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.
PROP. XXIX. Whatsoever the mind understands under the form of eternity, it does not understand by virtue of conceiving the present actual existence of the body, but by virtue of conceiving the essence of the body under the form of eternity.
Proof.—In so far as the mind conceives the present existence of its body, it to that extent conceives duration which can be determined by time, and to that extent only has it the power of conceiving things in relation to time (V. xxi. II. xxvi.). But eternity cannot be explained in terms of duration (I. Def. viii. and explanation). Therefore to this extent the mind has not the power of conceiving things under the form of eternity, but it possesses such power, because it is of the nature of reason to conceive things under the form of eternity (II. xliv. Coroll. ii.), and also because it is of the nature of the mind to conceive the essence of the body under the form of eternity (V. xxiii.), for besides these two there is nothing which belongs to the essence of mind (II. xiii.). Therefore this power of conceiving things under the form of eternity only belongs to the mind in virtue of the mind's conceiving the essence of the body under the form of eternity. Q.E.D.
Note.—Things are conceived by us as actual in two ways; either as existing in relation to a given time and place, or as contained in God and following from the