He was not earning enough money from writing to make a living, forcing him to do a teaching job he did not much enjoy, and in 1933 he transferred to Fray's College in Uxbridge to teach French.
Vis viva (from the Latin for "living force") is an obsolete scientific theory that served as an elementary and limited early formulation of the principle of conservation of energy. It was the first (known) description of what we now call kinetic energy or of energy related to sensible motions.