It would drive me nuts to have someone instructing me through every move.
It was his schoolteacher voice, instructing.
If a negative value is specified, an error message is output, instructing you to abort execution.
He also studied the chemistry of combustion and of respiration, and made experiments in physiology, where, however, he was hampered by the "tenderness of his nature" which kept him from anatomical dissections, especially of living animals, though he knew them to be "most instructing."
As clerk (1795) and then as supercargo (1796, 1798, 1799) he made four long voyages; and, being an excellent navigator, he afterwards (1802) commanded a vessel, instructing his crews in lunar and other observations.