In his autobiography of 1940 Epstein recalled 'The Rock Drill' both in the first version depicted here, and in its final state: 'It was in the experimental pre-war days of 1913 that I was fired to do the rock-drill, and my ardour for machinery (short-lived) expended itself upon the purchase of an actual drill...and upon this I made and mounted a machine-like robot, visored, menancing, and carrying within itself its progeny, protectively ensconsed. Here is the armed, sinister figure of today and tomorrow. No humanity, only the terrible Frankenstein's monster we have made ourselves into...Later I lost my interest in machinery and discarded the drill. I cast in metal only the upper part of the figure'.