The world either breaks or hardens the heart.

[En vivant et en voyant les hommes, il faut que le cœur se briese ou se bronze.]

Nicolas Chamfort (1741-1794) French writer, epigrammist (b. Nicolas-Sébastien Roch)

Products of Perfected Civilization [Produits de la Civilisation Perfectionnée], Part 2 “Characters and Anecdotes [Caractères et Anecdotes],” ch. 3 (frag. 771) (1795) [tr. Finod (1880)]
    (Source)

(Source (French))

Attributed by Chamfort as a statement in a philosophical debate, made by M. D---. Finod's translation is very much a paraphrase, as is:

Contact with the world either breaks or hardens the heart.
[ed. Ballou (1882)]

More literal translations:

Living among men and observing them, the heart must either break or turn to bronze.
[tr. Merwin (1969)]

In living and in seeing men, the heart must break or be bronzed.
[Source]

Though attributed by Chamfort to "M. D----," he also used the phrase himself, and it is usually attributed to him. Toward the end of his life, he wrote:

Je m'en vais enfin, de ce monde où il faut que le cœur se briese ou se bronze.

[I am leaving at last from this world where the heart must break or become bronze.]