What does 'l'homme c'est rien l'oeuvre c'est tout' mean?

The sentence 'L'homme c'est rien. L'oeuvre c'est tout' means [The individual] man is nothing. The overall work [or mankind] is everything. In the Word-by-Word translation, the definite article 'le'* means 'the'. The noun 'homme' means 'man'. The demonstrative pronoun 'ce'* means 'this'. The verb 'est' means '[he/she/it] is'. The noun 'rien' means 'nothing'. The noun 'oeuvre' means '[overall or body of creative] work'. And the noun 'tout' means 'all, everything'.

*The letter 'e' drops before a Word that begins with a non-aspirated vowel.

At the end of his Sherlock Holmes story, "the red-headed league" Sir Arthur Conan Doyle attributes this to Gustave Flaubert (writing to George Sand).