Full Idea
I believe that 'unity' is one of the more difficult words in philosophy, for there are in things many hidden (occultae) unities that are obscure to us.
Gist of Idea
'Unity' is a particularly difficult word, because things can have hidden unity
Source
John Duns Scotus (Lectura [1298], I.17.2.4), quoted by Robert Pasnau - Metaphysical Themes 1274-1671
Book Reference
Pasnau,Robert: 'Metaphysical Themes 1274-1671' [OUP 2011], p.208
A Reaction
Some examples would be nice. Do the Earth and the Moon form a unity, because of gravity? How ponders whether whiteness and a white man are unified.