Answer: Crossing the Machsom is equivalent to receiving the first anti-egoistic screen. Such barriers exist between all levels, but we simply call them degrees.
The very first spiritual degree, “Machsom,” is so unique because the person has no idea of what bestowal is. However, after reaching it, he already begins to picture bestowal a little; he sees an example of the Upper One and imitates Him. The person already has some connection with the Creator. In contrast, when he rises to his first degree he has to break through this “barrier” while being totally blind.
From the 3rd part of the Daily Kabbalah Lesson 12/1/2010, Beit Shaar HaKavanot