1p19d.md (671B)
1 God (by Def. vi.) is substance, which (by Prop. xi.) 2 necessarily exists, that is (by Prop. vii.) existence appertains 3 to its nature, or (what is the same thing) follows from its 4 definition; therefore, God is eternal (by Def. viii.). Further, 5 by the attributes of God we must understand that which (by Def. 6 iv.) expresses the essence of the divine substance–in other 7 words, that which appertains to substance: that, I say, should 8 be involved in the attributes of substance. Now eternity 9 appertains to the nature of substance (as I have already shown in 10 Prop. vii.); therefore, eternity must appertain to each of the 11 attributes, and thus all are eternal. Q.E.D. 12 13