baumhaus.digital/Art, Cognition, Education/Human and arti(ficial|stic) intelligence/Session 3 :: Form(s) of intelligence/General Intelligence/Spearman's Universal Unity of the Intellective Function
Whenever branches of intellectual activity are at all dissimilar, then their correlations with one another appear wholly due to their being all variously saturated with some common fundamental Function (orgroup of Functions).
(Spearman, 1904, p.273 in "General Intelligence: Objectively determined and measured")