Sefer Kerem Yisroel relates that when the Me’or Einayim was learning under his mentor, the Baal Shem Tov zy’a, he once saw him preparing for a journey. He very much wanted to come along, so he stood next to the horse and waited for him to board.
When the Baal Shem Tov saw his student waiting, he said to him, ‘Young man, if you can tell me the difference between the tikkun made by Leah and the tikkun made by Rochel, you can come with me.’
The Me’or Einayim replied, ‘The difference is that what Leah accomplished with her tears, Rochel accomplished with simcha.’
The Baal Shem Tov immediately told him to board the wagon and travel with him.