For all types of reasons, I hadn't had a chance to swim in the Mediterranean all summer long. Here in Ashdod, we have a "Mehadrin" beach with separate hours for men and women. But, during the summer vacation, it's packed. Now, with vacation over, I took advantage the empty beach and went for a swim one late afternoon. When I came back to the shore, I saw an immobilized jellyfish that a wave had thrown onto the sand. I contemplated that if we could photograph the evil inclination, it would probably look like a jellyfish - gooey and unsightly.
The world is like a stormy sea. All kinds of waves throw you all over the place, no matter how strong a swimmer you are. You get stung all the time and you can hardly sea what's stinging you. But, when you walk into the study hall and begin learning Torah, your soul is on dry land. Now, like the jellyfish washed up on shore that you couldn't see so clearly in the water, your evil inclination becomes apparent in all its ugliness and it becomes immobilized.
But, if you do go for a swim, beware of the jellyfish. Likewise, the moment we close our Gemara, we must keep our eyes open for the evil inclination; its tentacles can really sting.