1p11a1.md (2295B)
1 Of everything whatsoever a cause or reason must be assigned, either for its 2 existence, or for its non–existence–e.g. if a triangle exist, a 3 reason or cause must be granted for its existence; if, on the contrary, it does 4 not exist, a cause must also be granted, which prevents it from existing, or 5 annuls its existence. This reason or cause must either be contained in the 6 nature of the thing in question, or be external to it. For instance, the reason 7 for the non–existence of a square circle is indicated in its nature, 8 namely, because it would involve a contradiction. On the other hand, the 9 existence of substance follows also solely from its nature, inasmuch as its 10 nature involves existence. (See Prop. vii.) 11 12 But the reason for the existence of a triangle or a circle does not follow from 13 the nature of those figures, but from the order of universal nature in 14 extension. From the latter it must follow, either that a triangle necessarily 15 exists, or that it is impossible that it should exist. So much is 16 self–evident. It follows therefrom that a thing necessarily exists, if no 17 cause or reason be granted which prevents its existence. 18 19 If, then, no cause or reason can be given, which prevents the existence of God, 20 or which destroys his existence, we must certainly conclude that he necessarily 21 does exist. If such a reason or cause should be given, it must either be drawn 22 from the very nature of God, or be external to him–that is, drawn from 23 another substance of another nature. For if it were of the same nature, God, by 24 that very fact, would be admitted to exist. But substance of another nature 25 could have nothing in common with God (by Prop. ii.), and therefore would be 26 unable either to cause or to destroy his existence. 27 28 As, then, a reason or cause which would annul the divine existence cannot be 29 drawn from anything external to the divine nature, such cause must perforce, if 30 God does not exist, be drawn from God's own nature, which would involve a 31 contradiction. To make such an affirmation about a being absolutely infinite and 32 supremely perfect is absurd; therefore, neither in the nature of God, nor 33 externally to his nature, can a cause or reason be assigned which would annul 34 his existence. Therefore, God necessarily exists. Q.E.D. 35 36