The Structure of Intellect (SI) model includes a Content dimension, Products dimension, and Operations dimension. It is represented as a cube with each of the three dimensions occupying one side. Each ability is defined by a conjunction of the three categories, occupying one cell in the three-dimensional figure. There are five categories of Content including visual, auditory, symbolic, semantic, and behavioral. Six categories exist in the Products dimension including units, classes, relations, systems, transformation, and implications. The five kinds of Operations include cognition, memory, divergent production, convergent production, and evaluation. The SI Theory is an open system such that it allows for newly discovered categories to be added in any of three directions. The 5 x 6 x 5 figure provides at least 150 possible abilities, with over 100 having been empirically verified. The model also suggests where new abilities may be discovered based on existing abilities. Because of Guilford’s contributions during his career, intelligence was shown to be incredibly complex. No longer was intelligence a monolithic global trait considered innate and absolute.