It's taking bare time.

He is 67 in chronological age, but has the mind and body of someone 55.

The necessity for its maker, if he wishes to remain in business, to produce an efficient machine which shall at the same time be cheap, and therefore must be as simple as possible, has acted as a kind of Geddes' Axe, (sic) sweeping away a number of inessential contrivances […]

Unlike the slerp techniques, this approach produces motions with rational point trajectories, the socalled rational motions. In kinematical geometry, these motions had been studied since the end of the 19th century (5,43,52].