… is from page vi of the 2002 Dover Publications edition of the 1896 English-language translation – The Crowd: A Study of the Popular Mind – of Gustave Le Bon‘s 1895 La psychologie des foules:
Every conclusion drawn from our observation is, as a rule, premature, for behind the phenomena which we see clearly are other phenomena that we see indistinctly, and perhaps behind these latter, yet others which we do not see at all.