He made the letter Tet king over hearing, and He bound a crown to it, and He combined one with another, and with them He formed Leo in the universe, Av in the year, and the left kidney in the soul (person), male and female.
He made the letter Yud king over action, and He bound a crown to it, and He combined one with another, and with them He formed Virgo in the universe, Elul in the year, and the left hand in the soul (person), male and female.
The letter Chet represents life (Chai, Chaim). By calling Chet a king over sight, we are reminded that the eyes are the windows to the living soul. By gazing into another's eyes, we gain greater awareness of the divine life within them. This, in turn, leads to an experience of higher love which is also connected with Chet.
The letter Tet represents good (Tov). In stating that Tet is a king over hearing, we learn the importance of listening to and reading only elavating things in order to refine our goodness. What we hear becomes a program for what we do.
The letter Yud represents unity (Y'chidah) with the Divine. Since Yud is a king over action, this teaches us that through our actions, through performing mitzvot (commandments), we unite ourselves with the Holy One.