The more a person gets to know his soul, the better he is able to recognize his Creator. The soul is derived from the divine and therefore takes pleasure in the good actions of a person and is pained by the bad ones.

A wise man said: “My son, know your soul and you will know your Creator”…. We see that the soul is happy and rejoices over good acts, and worries and feels sad about evil acts. It is natural for a person to be happy with something which is similar to them and to be uncomfortable with something which is their opposite. As such, given that the soul is divine, it is happy and rejoices over good acts that are similar to its nature – for all Godly acts are good – and is sad about evil acts because they go against its nature and are opposed to it. (Rav Yosef Albo, Sefer HaIkkarim 3:6)

A person knows for certain that he has a soul, an internal spiritual identity, even though he has never seen it with his physical eyes. Likewise, with his mind’s eye, a person can grasp belief in God, even though seeing God’s essence is impossible.

A person is certain that he has a living soul – that a soul exists within his body and animates it – for his body cannot live independently. For his body, alone, is as inanimate as an animal’s flesh and bones sitting in a pot or in a stew. Rather, the body is animated by the life force of the spiritual soul within it – a living spirit that is tied to the blood, as the verse states: “For the blood is the life [literally, the soul]” (Deuteronomy 12:23). A person is certain about this even though he never saw the essence of the soul, how it functions and what it is. Nevertheless, its existence is clear to him through his intellect. This is something he sees through his mind’s eye and this verification is as reliable as something he sees with his physical eyes. (Rabbi Menaĥem Mendel Schneersohn, Derekh Mitzvotekha, Ha’amanat Elokut 45a)