E4P26D
Demonstration — Part IV
Latin
Conatus sese conservandi nihil est præter ipsius rei essentiam (per propositionem 7 partis III) quæ quatenus talis existit, vim habere concipitur ad perseverandum in existendo (per propositionem 6 partis III) et ea agendum quæ ex data sua natura necessario sequuntur (vide definitionem appetitus in scholio propositionis 9 partis III). At rationis essentia nihil aliud est quam mens nostra quatenus clare et distincte intelligit (vide ejus definitionem in II scholio propositionis 40 partis II). Ergo (per propositionem 40 partis II) quicquid ex ratione conamur, nihil aliud est quam intelligere. Deinde quoniam hic mentis conatus quo mens quatenus ratiocinatur suum esse conatur conservare, nihil aliud est quam intelligere (per primam partem hujus) est ergo hic intelligendi conatus (per corollarium propositionis 22 hujus) primum et unicum virtutis fundamentum nec alicujus finis causa (per propositionem 25 hujus) res intelligere conabimur sed contra mens quatenus ratiocinatur nihil sibi bonum esse concipere poterit nisi id quod ad intelligendum conducit (per definitionem 1 hujus). Q.E.D.
English (Elwes 1883)
The effort for self--preservation is nothing else but the essence of the thing in question (III. vii.), which, in so far as it exists such as it is, is conceived to have force for continuing in existence (III. vi.) and doing such things as necessarily follow from its given nature (see the Def. of Appetite, III. ix. note). But the essence of reason is nought else but our mind, in so far as it clearly and distinctly understands (see the definition in II. xl. note. ii.); therefore (II. xl.) whatsoever we endeavour in obedience to reason is nothing else but to understand. Again, since this effort of the mind wherewith the mind endeavours, in so far as it reasons, to preserve its own being is nothing else but understanding; this effort at understanding is (IV. xxii. Coroll.) the first and single basis of virtue, nor shall we endeavour to understand things for the sake of any ulterior object (IV. xxv.); on the other hand, the mind, in so far as it reasons, will not be able to conceive any good for itself, save such things as are conducive to understanding.
Modern English
The *conatus* to preserve oneself is nothing but the essence of the thing (E3P7), which, insofar as it exists as such, is conceived to have the power to persist in existing (E3P6) and to do what necessarily follows from its given nature (see the definition of appetite in the Scholium to P9 of Part III (E3P9S)). But the essence of reason is nothing other than our mind insofar as it understands clearly and distinctly (see its definition in the Second Scholium to P40 of Part II (E2P40S2)). Therefore (by P40 of Part II (E2P40)) whatever we strive for under the guidance of reason is nothing other than to understand.
Now, since this *conatus* of the mind — by which the mind, insofar as it reasons, strives to preserve its own being — is nothing other than understanding (by the first part of this demonstration), this *conatus* to understand is (by the Corollary to P22 of this Part (E4P22C)) the first and sole foundation of virtue. Nor shall we strive to understand things for the sake of any end beyond that (E4P25); on the contrary, the mind, insofar as it reasons, will be unable to conceive of anything as good for itself except what conduces to understanding (by Definition 1 of this Part (E4D1)). Q.E.D.