IV. By attribute, I understand that which the intellect perceives of substance, as constituting its essence.
V. By mode, I understand the affections of substance, or that which is in another thing through which also it is conceived.
VI. By God, I understand Being absolutely infinite, that is to say, substance consisting of infinite attributes, each one of which expresses eternal and infinite essence.
Explanation.—I say absolutely infinite but not infinite in its own kind (in suo genere); for of whatever is infinite only in its own kind (in suo genere), we can deny infinite attributes; but to the essence of that which is absolutely infinite pertains whatever expresses essence and involves no negation.
VII. That thing is called free which exists from the necessity of its own nature alone, and is determined to action by itself alone. That thing, on the other hand, is called necessary, or rather compelled, which by another is determined to existence and action in a fixed and prescribed manner.
VIII. By eternity, I understand existence itself, so far as it is conceived necessarily to follow from the definition alone of the eternal thing.
Explanation.—For such existence, like the essence of the thing, is conceived as an eternal truth. It cannot therefore be explained by duration of time, even if the duration be conceived without beginning or end.
Axioms
I. Everything which is, is either in itself or in another.
II. That which cannot be conceived through another must be conceived through itself.