Francis Lieber, letter to Charles Sumner (May 28, 1847):
Where have you got the German way of long and multiplied notes from? I do not mean to animadvert, but merely ask. That subject of notes is a very difficult one. The French affected way of just mentioning the author, or the least possible word of a title at the bottom of the page, is silly. On the other hand, to let the text float on the notes, like a thin sheet of oil on a cup of water for a night lamp, interferes with the unity of the work and the quiet of the reader's mind, while it easily exposes the author to the suspicion of vanity. I often find it difficult to choose the proper mean.