Works of St. Anselm, tr. by Sidney Norton Deane, , at sacred-texts.com
We must believe in this Being, that is, by believing we must reach out for it.
BUT what does not believe cannot love or hope. It is, therefore, profitable to this human soul to believe the supreme Being and those things without which that Being cannot be loved, that, by believing, the soul may reach out for it. And this truth can be more briefly and fitly indicated, I think, if instead of saying, “strive for” the supreme Being, we say, “believe in“ the supreme Being.p. 138
For, if one says that he believes in it, he apparently shows clearly enough both that, through the faith which he professes, he strives for the supreme Being, and that he believes those things which are proper to this aim. For it seems that either he who does not believe what is proper to striving for that Being, or he who does not strive for that Being, through what he believes, does not believe in it. And, perhaps, it is indifferent whether we say, “believe in it,” or “direct belief to it,” just as by believing to strive for it and toward it are the same, except that whoever shall have come to it by striving for (tendendo in) it, will not remain without, but within it. And this is indicated more distinctly and familiarly if we say, “striving for“ (in) it, than if we say, ”toward“ (ad) it.
On this ground, therefore, I think it may more fitly be said that we should believe in it, than that we should direct belief to it.