All know there is butter in sour milk; one who knows how to churn can separate it. In fuel there is fire, but you cannot kindle it without rubbing pieces together. Unless you clean a dirty-looking looking glass, how can you see your face in it? Says Tuka.
Hinduism
Tukaram, Poem 2091
Source The Poems of Tukârâma, trad. J. Nelson Fraser et K. B. Marathe, 3 vol., 1909-1915, archive.org · Contents