Like a vendor of pots and pans

From A Treasury of Jewish Folklore by Nathan Ausubel.

An Author's Life After Forty

A young Talmudic scholar who had just completed a learned work came to Rabbi Elijah, the Gaon of Vilna, and begged him for a testimonial.

Rabbi Elijah regarded his visitor with gentle compassion.

“My son,” he said to him, “you must face the stern realities. If you wish to be a writer of learned books you must be resigned to peddle your work from house to house like a vendor of pots and pans and suffer hunger until you’re forty.”

“And what will happen after I’m forty?” asked the young writer, hopefully.

Rabbi Elijah smiled encouragingly, “By the time you’re forty you’ll be quite used to it!”