Grist to/for the mill(idiom)
(Useful experience, material, or knowledge.)
Hindi meaning:फ़ायदेमंद
Synonyms: Advantageous, Profitable, Expedient, Beneficial
Antonyms: Disadvantageous, Harmful, Unprofitable
Example: Bob writes the novels on his own experience, so everything that happens to him is grist to/for the mill.
Trick to remember: Mill workers ke liye grist to the mill kiya. 
