To live is not to breathe but to act. It is to make use of our organs, our senses, our faculties, of all the parts of ourselves which give us the sentiment of our existence. The man who has lived the most is not he who has counted the most years but he who has most felt life.
Rousseau's Émile: Or, Treatise on Education (ed. 1892)
Variant translation:The man who has lived most fully is not the one who has survived the most years, but the one who has been most aware of life.