  Speaking of substance in the sense of “true substance” separate from (and higher than) corporeal substance, Ibn Gabirol, in line with other Platonisms and contra Aristotle, is referring to a “higher realm.” However, unlike Plato, Ibn Gabirol focuses (with Neoplatonists) on the substances of Intellect and Soul(s)—which  is to say, the reality of all forms “in” the simple spiritual substances (of Intellect and Soul), not on forms per se (see section 5.1 above). In this sense, the spiritual simples are primarily not the forms (as we might expect in Plato), but (in Neoplatonic spirit) the Universal Intellect and Soul. Relatedly, unlike other Platonisms, Ibn Gabirol's higher realm is not theorized as a realm of forms but as a realm of form and matter (again see section 5.1 on how the talk of Intellect leads us to the talk of forms “in” matter). This also means that with Aristotle, Ibn Gabirol employs a lot more hylomorphic talk than Platonists (though applied to a completely non-Aristotelian “higher realm”).