Thomas Aquinas

“ Therefore it is owing to charity that faith is the foundation: so that charity is the foundation yet more than faith is (for the foundation is the first part of a building) and consequently it seems to precede faith. ”

“ Because the formal object of faith is the First Truth, by adhering to which we believe whatever is contained in the faith. Secondly, on the part of the subject, and thus faith is differentiated according as it is in various subjects. Now it is evident that faith, just as any other habit, takes its species from the formal aspect of its object, but is individualized by its subject. Hence if we take faith for the habit whereby we believe, it is one specifically, but differs numerically according to its various subjects. ”

“ For evidence induces the intellect to adhere to a truth, wherefore the firm adhesion of the intellect to the non-apparent truth of faith is called "evidence" here. Hence another reading has "conviction," because to wit, the intellect of the believer is convinced by Divine authority, so as to assent to what it sees not. Accordingly if anyone would reduce the foregoing words to the form of a definition, he may say that "faith is a habit of the mind, whereby eternal life is begun in us, making the intellect assent to what is non-apparent." ”

“ I answer that, As shown above, it is by human virtue that human acts are rendered good; hence, any habit that is always the principle of a good act, may be called a human virtue. Such a habit is living faith. For since to believe is an act of the intellect assenting to the truth at the command of the will, two things are required that this act may be perfect: one of which is that the intellect should infallibly tend to its object, which is the true ”

“ That which makes an animal live is inseparable from an animal, because it is its substantial form, viz. the soul: consequently a dead thing cannot become a living thing, and a living and a dead thing differ specifically. On the other hand that which gives faith its form, or makes it live, is not essential to faith. ”

“ We might also reply that it is accidental, namely on account of the disposition of the subject, that grace does not cause faith in one who has it already: just as, on the other hand, a second mortal sin does not take away grace from one who has already lost it through a previous mortal sin. ”

“ To be a foundation a thing requires not only to come first, but also to be connected with the other parts of the building: since the building would not be founded on it unless the other parts adhered to it. ”