This proposition has two parts. Part 1: Each Sefirah is one of the attributes... This explains what is visible. Part 2: Since He wanted that they should be known... This explains how that which is visible is perceived.
Part 1: Each Sefirah is one of the attributes... Each attribute (מדה, middah, a “measure”, “quality” or “trait”) is one part of His will, namely one of His powers. We may understand this by analogy. The body is composed of many different limbs, and someone who sees the body sees these limbs. On the other hand, the parts of the soul are not limbs but powers: these powers are the various faculties of the soul, such as memory, imagination and feeling. Someone who “sees” them (with spiritual vision) sees a variety of different powers. Similarly, when one sees what it is possible to see of the Supreme Will, what he sees are the powers of that Will. Each Sefirah is one of the attributes – one in the sense of being unique and separate. It is the revelation of His powers as separate attributes that distinguishes God’s chosen way of acting through the Sefirot from His intrinsic omnipotence, in which He brings everything about through his unitary, all-encompassing power.