We may search Henry D. Thoreau's writings in vain for the name of Voltaire, or for a hint of influence by him. However, it is impossible to make a parallel study of the lives and works of these men without seeing many similarities. Thoreau was not accustomed to naming the source of his ideas. His writings are full of quotations, and he seldom takes the trouble of telling his readers where he found them. If we consider these two men side by side, we find, in spite of striking divergence, that the points of contact or likeness are more prevailing than are the points of difference.