In Tehillim, David HaMelech mentions that HaShem 'bent' the Heavens over the Earth, Rabbi Tatz continued. Down here, in this world, there is a bend, things aren't linear, and so things that may be close may be beyond our view, while things that are far away may in fact be visible.
Just think about the image illustrated here. Think of a distant vista of rolling hills. Yes, you can see the hilltops, but who knows what the valleys in the middle conceal? Whatever is in the valleys may be closer than the more distant hilltops, but it is hidden from sight. Similarly, whatever is directly behind you is beyond your field of vision, yet it is extremely close to you.
Rabbi Tatz goes on to discuss how this very 'bend' in the world is the yetzer hara, the evil urge, the primordial serpent, which Moshe Rabbeinu is commanded to take in his hand, at which point it becomes a staff he is meant to use.
Let's look for a moment at a story told by the Ben Ish Hai to illustrate the power of the yetzer hara. R' Hayyim (The Ben Ish Hai) tells of a teacher of young men in yeshivah. It was the 17th of Tammuz and he could tell the boys were weary and weak from fasting. So the teacher said, "You know, you are so weak and tired, perhaps we won't learn today. Instead, we will play cards." The boys were understandably very excited and not a little bit incredulous at this statement, "There's only one problem," the Rebbe went on, "one of you will need to teach me the rules." The boys were falling over one another to teach him the rules, and so they played energetically for a good half hour until the Rebbe stopped them. "I didn't want to trouble you, you seemed so weak today, but it appears you have plenty of energy after all, enough with the cards, let's open the books." What could they say? So they opened the books and learned as usual.
The moral of the story is either: (1) Don't fall for an obvious trick of the Rebbe, or (2) Don't fall for an obvious trick of the Yetzer Hara. As Rabbi Tatz explained above, the power of the Yetzer Hara, the evil urge, is in the ability to make things feel far away from you. We see in Kohelet that the lazy person, the atzel, finds excuses why it's too dangerous to travel to learn from his rebbe, even if the travel is no further than down a few stairs to the sitting room. The Yetzer Hara makes us feel like accomplishing a mitzvah is so very very difficult, so very very far beyond our reach. In reality it is very close to us.
This is what Mosheh Rabbeinu tells us in the Torah, the matter is exceedingly close to you, it is [already] in your mouths and in your hearts to do... No one needs to ascend to the heavens to bring it down to you, no one needs to cross the sea to bring it back. [all that has already been done.] These are all tricks of the Yetzer Hara. Don't fall for it, or you'll feel like a sheepish yeshivah bochur who just won a game of cards against his rebbe, elated for a moment, before he realizes he's in for it.