In Chapter I of Shri Sai Satcharita, the philosophical significance of grinding by Shirdi Sai Baba is described as follows.
“Baba lived in Shirdi for about sixty years and during this long period, He did the business of grinding almost every day, not however wheat alone; but the sins, the mental and physical afflictions and the miseries of His innumerable devotees. The two stones of His mill consisted of karma and bhakti; the former being the lower one and the latter, the upper one. The handle, with which Baba worked the mill, consisted of dhyan. It was the firm conviction of Baba that knowledge or self-realization is not possible, unless there is the prior act of grinding of all our impulses, desires, sins; and of three gunas, viz. Sattva, Rajas and Tamas, and the Ahankar, which is so subtle and therefore, so difficult to get rid of.”
Shri Satchidananda Sadguru Sainath Maharaj Ki Jaya.
Dr.Mahesh Chandra Panda
Shirdi Sai Baba devotee