Adam Clarke on Ecclesiastes 9:18

Wisdom is better than weapons of war - So proved in the case of Archimedes.

But one sinner - Such as the Roman butcher above mentioned.

Destroyeth much good - Such as were the life and skill of the Syracusan mathematician. One sinner has often injured the work of God; one stumbling-block has sometimes destroyed a revival of religion. Sin acts like a ferment; whatever comes in contact with it, it assimilates to itself.