S. R. Faruqi:

This verse is in no need of explanation. For the spirit to be vexed with the body is a commonplace theme. The spirit is a prisoner and the body a prison-house-- this theme came into our poetry through the Sufis, and became very well accepted. There's no expectation that anything new will be possible in it. But Mir, by calling the body ek ṭokrī miṭṭī , has touched the height of the metaphor, and has also showed a mastery of pithiness of speech. No matter how beautiful and delicate the body might be, in any case it's still dirt. Thus in the metaphor the 'vehicle' remains entirely suitable, and he has also shown complete disdain for the body. In this way the 'vehicle' is more powerful than the 'tenor', but here its power is in the fact that it is more contemptible and low than the 'tenor' (the body).

Then in the first line, by calling the body ḳhākī he has also arranged a complete affinity. Otherwise, several forms for the line were possible that would have conveyed the meaning:

(1) ab jān jism-e kuhnah se tang ā gaʾī bahut
(2) ab jān jism-e zār se tang ā gaʾī bahut
(3) ab maḥnat-e badan se hai jāñ tangiyoñ meñ qaid

And so on. But the pleasure of the affinity would have drained away. In the same way, since we assume that the spirit is imprisoned in the body, in the first line tang too is a word with affinity.

In miṭṭī kī ṭokri ḍhonā an image of hard labor, and especially the forced labor of begār (that is, for which there would be no pay), is created. The spirit, carrying the body, wanders around, and it's clear that the spirit gets nothing from this; thus the spirit has been seized for 'begar'. This theme belongs to Maulana-e Rum; in the 'Masnavi' the Maulana says [in Persian]:

'But the 'begar' of the body full of bones--
Don't always keep imposing it on the spirit.'

Atish, profiting from Mir's verse (and possibly that of Maulana-e Rum) has well composed:

us mashqat se use ḳhāk nah hogā ḥāṣil
jāñ ʿabaṡ jism kī begār liye phirtā hai

[from that practice it will get nothing/'dust'--
the life/spirit vainly goes around doing the 'begar' of the body]

The rareness of the metaphor, the 'dramaticness' of the tone, and the insha'iyah style, all raise Mir's verse far beyond Atish's. But Atish too has well used the word ḳhāk , and his verse can definitely be placed over against Mir's.

Yaganah too has changed the image, and composed a fresh idea:

yās ab tang ā gaʾe is malgajī poshāk se
jāmah-e tan dhajjiyāñ lene ke qābil ho gayā

[oh despair, we have now become vexed with this filthy garment
the robe of the body has become fit for tearing up]

FWP:

SETS
MOTIFS
NAMES
TERMS == FRESH WORD

That little Hindi-side word ṭokrī , with its simplicity and everydayness, is a delight in itself. It certainly deserves credit as a 'fresh word'-- one that Mir himself hardly uses, and that never appears in Ghalib's whole divan.

Note for translation fans: Isn't it a pity that for ḳhākī we can't just say 'dusty'? It would be perfect in a literal sense. But of course in English it has come to mean 'covered with dust', while the Urdu has the general sense of 'pertaining to dust', or (in view of Islamic theology) 'made of dust'. So even though 'dust-made' is awful-sounding, I've forced it to happen.

And to make up for that frustration in the first line, in the second line English has given us a nice punchy little gift. The meanings of miṭṭī include both the neutral 'earth, soil', and the negative 'filth, excrement'. English offers us 'dirt'-- a word that elegantly straddles the border between them.