To do big things, it is essential not to be such a great genius; one must not be above men, one must be with them.

[Pour faire de grandes choses, il ne faut pas être un si grand génie: il ne faut pas être au-dessus des hommes; il faut être avec eux.]

Charles-Lewis de Secondat, Baron de Montesquieu (1689–1755) French political philosopher

Pensées Diverses [Assorted Thoughts], # 1083 / 1224 (1720-1755) [tr. Clark (2012)]
    (Source)

(Source (French)).

Source of the more commonly quoted, 21st Century paraphrase:

To become truly great, one has to stand with people, not above them.