Existence not only requires excrement (as such: a cyclic element): a body is also, and makes itself, its own excretion. A body spaces itself, a body expels itself, identically. It exscribes itself as body: being spaced, it’s a dead body; being expelled, it’s a filthy body.

—Jean-Luc Nancy1

We are made as the filth of the world, the dirt wiped off by all, even until now.

—1 Corinthians 4:13

Filth (n.)—Old English fylð “uncleanness, impurity, foulness,” from Proto-Germanic *fulitho (cognates: Old Saxon fulitha “foulness, filth,” Dutch vuilte, Old High German fulida), noun derivative of *fulo- “foul.”

 Foul (adj.)—Old English ful “rotten, unclean, vile, corrupt, offensive to the senses,” from Proto-Germanic *fulaz (cognates: Old Saxon and Old Frisian ful, Middle Dutch voul, Dutch vuil, Old High German fül, German faul, Gothic füls), from PIE *pu- (2) “to rot, decay,” perhaps from the sound made in reaction to smelling something bad.

Old English ful occasionally meant “ugly” (as contrasted with fæger (adj.), modern fair (adj.)), and this sense became frequent in Middle English. The cognate in Swedish is the usual word for “ugly.”

Filthy (adj.)—late 12c., fulthe, “corrupt, sinful,” from filth + -y. Meaning “physically unclean, dirty, noisome” is from late 14c. Meaning “morally dirty, obscene” is from 1530s. In early use often hardly more emphatic than the modern dirty, it is now a violent expression of disgust [OED].

Filth (n.)—(1) The quality or state of being foul; a filthy state or condition; filthiness; in pl. foul treatment, indignities. Obs. (c. 1300).
_____(2) Foul matter: (a) Putrid matter, corruption, rottenness; in later use, purulent matter, pus. Obs. (b) Uncleanly matter, dirt. Now only in a stronger sense, expressing violent disgust: loathsome dirt. Rarely in pl. filth of various kinds, filthy matters. (c) Vermin (formerly pl.). In modern use restricted to insect parasites.
_____(3) Figure: (a) Moral defilement, vileness; corruption, pollution; obscenity. (b) pl. Moral impurities, corrupt or impure actions, transgressions. Obs. (c) Foul or obscene language; vile or loathsome imputations.
_____(4) Said of a person: A vile creature; a scoundrel; a slut, drab, whore. Obs. 1608 Shakespeare, King Lear, xvi, 38: “Filths savor but themselves.”