When we generalize, we form concepts of an ever-widening scope of application, organized in generalization hierarchies, like the taxonomy of the species.
This generalizing process culminates in the superclass Being, all other classes being subclasses, a structure that has evolved from object-oriented modelling and programming methods in business.
Generalization thus lies at the core of the Theory of Everything, as a megasynthesis of all knowledge in all cultures and disciplines at all times.
Before 1751, ‘render general, make more general, bring under a general description’, probably a new formation from general, because Middle English had generalisen before 1425, as French généraliser is not found before 1578.
Note. On the recommendation of the Oxford English Dictionary, I prefer generalize to generalise, even though the latter is generally regarded as standard in British English, being more influenced by the French than the original Greek verb-forming suffix -izein.