The two primary powers of the soul are intelligence and will. The three aspects of intelligence are knowledge, memory and reasoning. Passions are also inclinations originating from the soul.
First, I know that I am, that I exist. Through my senses I see many individual entities in the world, numberless trees, stars, animals and humans. This is sense knowledge retained in my memory in the form of images, sounds, smell, touch and taste. My intelligence has also the power of abstraction by which we form universal ideas of the nature of things. For example, I have the idea of human nature regardless of size, sex, color and number.
I also have memory or the ability to store sense data, information and truths. Without memory I would not be able to reason because I would not have the ability to move from one thing or idea to another in the process of reasoning.
"Reason is the capacity for consciously making sense of things, applying logic, establishing and verifying facts, and changing or justifying practices, institutions, and beliefs based on new or existing information. It is closely associated with such characteristically human activities as philosophy, science, language, mathematics, and art and is normally considered to be a definitive characteristic of human nature." (Wikipedia: Reason) There is also in me intuitive knowledge that good is to be done and evil avoided. At times, there is doubt as to the dictate of conscience, so I use reason to clarify the truth.
The will is the power to decide to move or not to move in the direction of the good, true and beautiful. For example, if I see an apple on tree, I know from previous knowledge that it is good to eat, so I may decide to pick and eat it. On the other hand, I may decide not to act because the apple tree is my neighbor's property. Another example, I may be attracted the the world view of Buddhism. There is certainly some truth in the teaching of the Buddha but not the complete truth because it has not idea of a personal God. Buddha sought truth within his soul and the nature of man is not distinct reality from the All. So, I turn away from Buddha toward the clear truth found in Christ who said I am the Way, the Truth and the Life.