 Another important issue pertinent to the ontology of mathematics is the nature of algebraic objects. An algebraic unknown (or, an algebraic variable, as we call it today) can indifferently refer to either a number or a geometrical magnitude. So, the nature of an algebraic object is not the same as either numbers or geometrical shapes. Unfortunately, the hybrid ontology of this special type of mathematical objects has rarely (if at all) been discussed as an ontology different from those of numbers and magnitudes. But it has been argued that the familiarity of philosophers such as al-Fārābī and Avicenna with the algebraic theory put forward by al-Khwārizmī (d. 850) in his Kitāb al-jabr wa al-muqābala inspired them to develop a general ontology of things (ashyāʾ) that is neither Platonic nor Aristotelian (R. Rashed 1984a; 2008; 2015: 716–18; 2018).