The reason that the will to receive devolves by means of the aforementioned four levels, Atzilut (Emanation), Beria (Creation), Yetzira (Formation), and Asiya (Actualization), is due to an important principle that applies to the vessels: It is the expansion of the light and its subsequent removal that renders the vessel suitable for its function. This means that as long as the vessel has not been separated in any way from its light, it is encompassed in the light and subsumed within it like a candle in the presence of a torch.
This subsummation occurs because the vessels and light are complete opposites from one extreme to the other. The light is shefa that emanates from His essence yesh miyesh. From the perspective of the intent to create that stems from Ein Sof, blessed be He, the light is intended purely to grant shefa and contains nothing of the will to receive. The vessel is the opposite, as it is composed of the ultimate desire to receive that shefa, a desire that is the entire root of the created being, containing no ability to give whatsoever.