Spiritual attainment comes very slowly because it is the manifestation of a new structure within a person. We cannot even imagine what it means to acquire a second nature. This does not exist and has never existed in our world, in the entire Universe; it has never happened over the entire course of history.
The nature that we acquire is built very gradually on the basis of many individual details and states, which appear inside us. This is the upper Light’s rigorous, slow, and incessant work upon us.
There is a latency period in the process of spiritual attainment whereby much work on the preparation of spiritual properties takes place within man. This literally represents a new birth.
But we are not just to be born additionally in the spiritual world; we need to go through changes on all the levels of our desire: 0 (Shoresh, root), 1 (Aleph), 2 (Bet), 3 (Gimel), and 4 (Dalet). Only then will we feel that something is happening to us. Until this last level 4 (Dalet), everything happens in an unclear manner that is concealed from us.
It is as if we were going from the zero point of creation to the state when our desire for the spiritual slightly begins to awaken. This is not even the actual desire; it is a certain understanding of this desire, a separation from whatever now exists in us. At first this happens in one’s sensations and then in the mind. This is how the upper Light influences us.
This is why it is unrealistic to expect for everything to happen in a second, even though one must wish for it with all his might. In other words, every moment must be the last one, and if he did not succeed, then let it be the beginning of the next moment.
From the Daily Kabbalah Lesson 11/26/2010, Baal HaSulam, Letter 52