The ability of the Sefirot to be represented in the images and likenesses of prophecy derives from the Sefirah of Malchut, which is the root of the lower realms. It is through Malchut that all are made in the form in which they are made. Accordingly, the Kabbalistic sages said it is impossible to ascend or receive except through Malchut. Even the very forms of the images themselves provide knowledge of the wisdom with which the worlds are governed.
For through them, we can know how the Shechinah (God’s Indwelling Presence) needs to govern for the sake of the matter (represented in a given image) and to bring it down to the level of the lower realms. From and through Malchut, it is possible to gain knowledge of the levels above it, these being the actual powers and attributes of God’s government (i.e. the Sefirot themselves, as opposed to the images through which these powers and attributes appear when seen through the lens of Malchut).