Spinoza's Ethics: II.P24: Affects Not Parts Constitute the Human Mind

Spinoza further describes that the human mind does not understand the parts which make up the human body. In his demonstration, he shows that it is not the parts which constitute the human mind, but instead, the relationships of the parts - and particularly when those relationships are changing. It is in this movement which alters a relationship that drive an affect. These affects are the experience of the expressiveness of God within the human body. This identification of expressiveness through the affects is the nature of the human mind and the basis for adequate understanding.

Mens humana partium corpus humanum componentium adæquatam cognitionem non involvit.

Translated as,

The human mind does not involve an adequate understanding of the parts composing the human body.

DEMONSTRATIO: Partes corpus humanum componentes ad essentiam ipsius corporis non pertinent nisi quatenus motus suos certa quadam ratione invicem communicant (vide definitionem post corollarium lemmatis 3) et non quatenus ut individua absque relatione ad humanum corpus considerari possunt. Sunt enim partes humani corporis (per postulatum 1) valde composita individua quorum partes (per lemma 4) a corpore humano, servata omnino ejusdem natura et forma, segregari possunt motusque suos (vide axioma 1 post lemma 3) aliis corporibus alia ratione communicare adeoque (per propositionem 3 hujus) cujuscunque partis idea sive cognitio in Deo erit et quidem (per propositionem 9 hujus) quatenus affectus consideratur alia idea rei singularis, quæ res singularis ipsa parte ordine naturæ prior est (per propositionem 7 hujus). Quod idem præterea etiam de quacunque parte ipsius individui corpus humanum componentis est dicendum adeoque cujuscunque partis corpus humanum componentis cognitio in Deo est quatenus plurimis rerum ideis affectus est et non quatenus corporis humani tantum habet ideam hoc est (per propositionem 13 hujus) ideam quæ humanæ mentis naturam constituit atque adeo (per corollarium propositionis 11 hujus) humana mens partium corpus humanum componentium adæquatam cognitionem non involvit. Q.E.D.

Translated as,

The parts composing the human body do not pertain to the essence of the body itself unless insofar as they communicate their motions by some specific way interactively (see definition after the corollary of lemma 3) and not insofar as they are able to be considered as individual parts from relation to the human body. For they are parts of the human body (by postulate 1) firmly composed individuals whose parts (by lemma 4) from the human body, altogether saving the nature and form of the same, are able to segregate and communicate their motions (see axiom 1 after lemma 3) to other bodies by another way to such a degree (by IIP3) will be the idea of whatsoever part or understanding in God and indeed (by IIP9) insofar as an affect is considered by another idea of a singular thing, which is a singular thing prior by the part itself in the order of nature (by IIP7). Which the same meanwhile even concerning whatsoever part of the individual itself composing the human body must be said to the extent that the understanding of whatsoever part composing the human body is in God insofar as it is the affect by more ideas of things and not insofar as it has only the idea of the human body, that is (by IIP13) the idea which constitutes the nature of human mind and to the extent (by IIP11C) the human mind does not involve the adequate understanding of the parts composing the human body.