Once there was a man who ground a big stone with great effort. He made a small toy bull out of it after days and months of labour. The effort being made was strenuous, yet the gain expected was trivial.
So are the people from all walks of life.
Grinding a stone refers to learning seriously and diligently.
To make a small toy bull applies to the illusive fame and the inducement of the mutual criticism.
A scholar should endeavour himself to serious studying to get wide and extensive knowledge. Furthermore, he has to put his learning into practice so as to obtain some fulfilment. The goal must not be the illusive fame, complacence and arrogance, which breed only sins and calamities.