 Geometrical objects are similar to numbers, but they differ insofar as their species are infinite. Avempace mentions infinite figures “resulting from [intersecting] the straight line with the circle, either cylinder or conic”. Primary genera of geometry are the line, the surface and the body, and Avempace denies any parallelism to the swimming, walking and flying characteristics of animals—he uses the term tanasub, ‘proportional’, opposite to tawatu’, ‘univocal’ (IB-BA: 74. 16–20).