It is known that Baal HaSulam respected materialistic psychology since it, as it were, opens the way to the wisdom of Kabbalah. Psychology speaks about the powers of a living creature’s soul, which exists in our world at the level of a beast.
The wisdom of Kabbalah speaks about the development of these forces in a person when he begins to evolve thanks to the spiritual spark that awakens in him and the Light that Reforms. This Light influences a person as if from outside, but it actually awakens within him according to his plea.
And then a person begins to develop and see what forces of the divine soul, that is, the forms of bestowal develop in him, and in what directions and ways. Over the course of their development, he discovers them in the form of Gematria (numerical value) and names, and he already feels within him what forces come from the right side or from the left. These are not the same sides as in our world, but the right or and left lines in their spiritual root. All of this immediately connects to a person with the language of branches. But all of them are inner forces of the soul. This is already spiritual psychology, the wisdom of Kabbalah.
From the 2nd pat of the Daily Kabbalah Lesson 11/16/2011, The Zohar