(1366-1424) expanded on Al-'Arabi's work, using it to describe a holistic view of the universe which reflects "unity in diversity and diversity in unity" (al-wahdah fi'l-kathrah wa'l-kathrah fi'l-wahdah).

Leibniz used the phrase as a definition of "harmony" (Harmonia est unitas in varietate) in his Elementa verae pietatis, sive de amore dei 948 I.12/A VI.4.1358. Leibniz glosses the definition Harmonia est cum multa ad quandam unitatem revocantur which means the 'Harmony' is when many [things] are restored