You will find that with regard to the first aspect, which is the indispensable means necessary for his subsistence, and the second aspect, which is the means connected to animal lusts that go beyond the measure for his subsistence, he receives and is nourished by things that are lower than him, which are the mineral, vegetable, and animal. However, the third aspect, which is human desire such as power and honor, he receives and is nourished from his own kind, who are equal to him. And the fourth aspect of nourishment, which is knowledge, he receives and is nourished from a loftier aspect than his own kind, that is, from wisdom and intellect themselves, which are spiritual.
Heart of Understanding
Baal HaSulam's Preface to Zohar 20:1