Bion first referred to his concept of the Grid in Elements ofPsycho-Analysis (1963); he continued to develop his ideas in later works, Transformations (1965), Two Papers: The Grid and Caesura (1977), and Taming Wild Thoughts (1997). The Grid represents that aspect of α-function which mediates elements that are subject to the reality principle and to what Freud (1911b) referred as “secondary process”. The Grid is a mathematical device consisting of a plane covered by crossed lines, which creates the image of boxes or squares (containers), or a grating (Bion, 1997, p. 4) that extends both vertically and horizontally. They may be considered “thought bins” to store categories of thoughts and emotions. Every step in the transformational process moves from one bin to another diagonally downward and is constrained by a vertical and a horizontal axis. The vertical axis (the genetic axis) of the Grid designates the progressive transformative sophistication of developing or evolving thoughts as it moves downward, whereas the horizontal axis designates the act of thinking the thoughts—that is, the use to which the thoughts are being put. It represents the activity of the mind in what Freud termed secondary process. Put another way, the Grid is the container for transformed thoughts, the contained.