Kether heads the central column of the tree, which is known metaphorically speaking as the "Pillar of Mildness" and is associated with Hebrew letter Aleph, "the breath", and the air element. It is a neutral one, a balance between the two opposing forces of male and female tendencies. Some teachings describe the sefirot on the centre pillar as gender-neutral, while others say that the sefirot vary in their sexual attributions.