purely rational considerations, not to divine commands and prohibitions. Here, as throughout
the first three books, Aquinas is glad, at the end of a piece of reasoning, to quote texts showing
that reason has led him to a conclusion in harmony with the Scriptures, but he does not appeal
to authority until his result has been reached.
There is a most lively and interesting discussion of voluntary poverty, which, as one might
expect, arrives ultimately at a conclusion in harmony with the principles of the mendicant
orders, but states the objections with a force and realism which shows them to be such as he had
actually heard urged by the secular clergy
He then passes on to sin, predestination, and election, on which his view is broadly that of
Augustine. By mortal sin a man forfeits his last end to all eternity, and therefore eternal
punishment is his due. No man can be freed from sin except by grace, and yet the sinner is to be
blamed if he is not converted. Man needs grace to persevere in good, but no one can merit
divine assistance. God is not the cause of sinning, but some He leaves in sin, while others He
delivers from it. As regards predestination, Saint Thomas seems to hold, with Saint Augustine,
that no reason can be given why some are elected and go to heaven, while others are left
reprobate and go to hell. He holds also that no man can enter heaven unless he has been
baptized. This is not one of the truths that can be proved by the unaided reason; it is revealed in
John III, 5. *
The fourth book is concerned with the Trinity, the Incarnation, the supremacy of the Pope, the
sacraments, and the resurrection of the body. In the main, it is addressed to theologians rather
than philosophers, and I shall therefore deal with it only briefly.
There are three ways of knowing God: by reason, by revelation, and by intuition of things
previously known only by revelation. Of the third way, however, he says almost nothing. A
writer inclined to mysticism would have said more of it than of either of the others, but
Aquinas's temperament is ratiocinative rather than mystical.
The Greek Church is blamed for denying the double procession of the Holy Ghost and the
supremacy of the Pope. We are warned that, although Christ was conceived of the Holy Ghost,
we must not
* " Jesus answered, verily, verily, I say unto thee, except a man be born of water and of the
Spirit, he cannot enter into the kingdom of God."