The concept of "universal," defined here as a tool for measuring angles, is also deeply examined in philosophy as a general principle or abstract entity. Authors such as Victor Cousin highlighted its role in providing particular things with unity, while Bertrand Russell viewed it as a general notion embedded in language and thought.
Hegel questioned whether universals exist independently of the mind, and William James pointed out the intertwining of subjective and objective ideas. These viewpoints reveal a tension between empirical measurement and abstract reasoning, showing how the theme connects tangible tools with metaphysical exploration. The interaction between these aspects highlights the dual character of universals as both practical devices and philosophical concepts.