Q. 141. Why then do we say a soul is dead while in a state of mortal
sin?
A. We say a soul is dead while in a state of mortal sin, because in that
state it is as helpless as a dead body, and can merit nothing for
itself.

Q. 142. What does our "understanding" mean?
A. Our "understanding" means the "gift of reason," by which man is
distinguished from all other animals, and by which he is enabled to
think and thus acquire knowledge and regulate his actions.

Q. 143. Can we learn all truths by our reason alone?
A. We can not learn all truths by our reason alone, for some truths are
beyond the power of our reason and must be taught to us by God.

Q. 144. What do we call the truths God teaches us?
A. Taken together, we call the truths God teaches us revelation, and we
call the manner by which He teaches them also revelation.

Q. 145. What is "Free Will"?
A. "Free Will" is that gift of God by which we are enabled to choose
between one thing and another; and to do good or evil in spite of reward
or punishment.

Q. 146. Have brute animals "understanding" and "free will"?
A. Brute animals have not "understanding" and "free will." They have not
"understanding" because they never change their habits or better their
condition. They have not "free will" because they never show it in their
actions.