By attribute, I mean that which the intellect perceives as constituting the essence of substance.
V.

By mode, I mean the modifications[1] of substance, or that which exists in, and is conceived through, something other than itself.
[1] "Affectiones" VI.

By God, I mean a being absolutely infinite--that is, a substance consisting in infinite attributes, of which each expresses eternal and infinite essentiality.
Explanation--I say absolutely infinite, not infinite after its kind: for, of a thing infinite only after its kind, infinite attributes may be denied; but that which is absolutely infinite, contains in its essence whatever expresses reality, and involves no negation.
VII.

That thing is called free, which exists solely by the necessity of its own nature, and of which the action is determined by itself alone.

On the other hand, that thing is necessary, or rather constrained, which is determined by something external to itself to a fixed and definite method of existence or action.
VIII.