Dear Chaim,

Shabos Shel Mi explains this Gemara's Agadah in a parable form, in two different ways:

1) Rabah sat in the sea, which depicts the world, and looked for 'Mashcha' - which can mean oil (which is used for pleasure). Ula told him that one should enjoy in this world only pleasures that are derived from Mitzvos, for example eating a Se'udas Mitzvah - and that even such a pleasure must be taken in measure. Ula agreed, commenting that he indeed enjoys the pleasure of eating Se'udas Mitzvah only at infrequent times ('Mis'asek'), such as on Erev Yom Kipur and Shavu'os.

2) Water refers to Torah. Rabah was measuring how large the Torah is, and how one can never complete it. Ula said that our duty is only to measure Mitzvos, which must be completed. There is no reason to measure Torah since it is indeed immeasurable. Rabah replied that he was aware of that; he was only measuring the distractions of the world ('Misasek b'Alma'), which keep one from learning Torah properly.

All the best,

Reuven Weiner