Sentence:  We learn of the cruelty of some school or child-factory from journalists; we learn it from inspectors, we learn it from doctors, we learn it even from shame-stricken schoolmasters and repentant <WSD>sweaters</WSD>; but we never learn it from the children; we never learn it from the victims. 
Meaning of the word marked with <WSD> tags:  One who or that which causes to sweat.