Saint Anselm

“ All power follows the will. For, when I say that I can speak or walk, it is understood, if I choose. For, if the will be not implied as acting, there is no power, but only necessity. For, when I say that I can be dragged or bound unwillingly, this is not my power, but necessity and the power of another ”

“ Wherefore, since whatever God has he has perfectly of himself, he is most of all to be praised for the good things which he possesses and maintains not by any necessity, but, as before said, by his own infinite unchangeableness. ”

“ Therefore, likewise, that man who will be also God since every good thing which he possesses comes from himself, will be holy not of necessity but voluntarily, and, therefore, will deserve praise. For, though human nature will have what it has from the Divine nature, yet it will likewise have it from itself, since the two natures will be united in one person.
Boso. You have satisfied me on this point; and I see clearly that it is both true that he could not sin, and yet that he deserves praise for his holiness. ”