A few extracts from Luther's dismantling of Erasmus on free will:
...your book is, in my estimation, so mean and vile, that I greatly feel for you having defiled your most beautiful and ingenious language with such vile trash; and I feel an indignation against the matter also, that such unworthy stuff should be borne about in ornaments of eloquence so rare; which is as if rubbish, or dung, should be carried in vessels of gold and silver.
In the mean time, I admonish you to correct your tongue, and your pen, and to refrain henceforth from using such expressions. For, how upright and honest soever your heart may be, your words, which are the index of the heart, are not so.
These statements of yours are without Christ, without the Spirit, and more cold than ice: so that, the beauty of your eloquence is really deformed by them.
...and so worthless a book on "Free-will" I never saw, excepting the elegance of the language.