Of God and His Creatures

It is not 'evil in itself,' that is, not absolutely, universally, and under all circumstances. Neither is it universally and under all circumstances good; but where there is a good, of nature established, there is somehow, and under some conditions, a natural and good way of attaining to that good; and where there is for all men but one way of attaining that good, the said way cannot be evil for ever and for all.

Of God and His Creatures: 3.126