Not all, only a few as flowers bloom and grow
How many remain hid in the dust, none may e’er know
sab kahan kuch lala-o-gul mein numayan ho gain
khak mein kya suratein hongi k pinhan ho gain
(all wherefore? just a few tulips-and-roses in manifested are
dust/dirt in-it what faces must-be that merged-hidden are)
For every ‘great’ person, numberless equally worthy remain obscure to history. Such is the tragedy of life.
‘Khak‘ literally means dust, but is used in Urdu to the same effect as ‘ashes’ is in English, i.e., as a symbol of mortality and impermanence of the body. So here the nuances are several; Ghalib layers the couplet with a potential for diverse interpretations. Of which I have chosen the most identifiable one.