Heraclitus the philosopher lived in the 500s, but Callimachus the poet wrote his lament in the 200s. His friend called Heraclitus was a real person, a scholar, but not the philosopher from centuries before. Cory's famous (somewhat inflated) 1845 translation has been given above, and so has a more modern and closer translation of the Callimachus. Here is the original.
Eipe tis, Hêrakleite, teon moron, es de me dakru
êgagen; emnêsthên d' hossakis amphoteroi
hêlion en leskhêi katedusamen; alla su men pou,
xein' Halikarnêsseu, tetrapalai spodiê.
Callimachus was librarian at Alexandria, and uttered the useful maxim megalon biblion megalon kakon "a big book is a big evil".