Dee had always, working with and under him, a number of young students and assistants, who were admitted more or less to his inner counsels. If they proved apt and diligent, he would reward them with promises of alchemical secrets, "whereby they might honestly live"; once he promised £100, "to be paid as soon of my own clere hability, I myght spare so much." This was a very safe provison. Generous as he was, lavish to a fault, money never stuck near him, nor was it of the least value in his eyes, except as a means of advancing science and enriching others.

Naturally, jealousies arose among the assistants. They would suddenly depart from his service, and spread ignorant and perverted reports of his experiments. Roger Cook, who had been with his master fourteen years, took umbrage "on finding himself barred from vew of my philosophical dealing with Mr. Henrick." He had imagined himself the chosen confidant, for to him Dee had revealed, December 28, 1579, what he considered a great alchemical secret "of the action of the elixir of salt, one upon a hundred." Roger was now twenty-eight, "of a melancholik nature, and had been pycking and devising occasions of just cause to depart on the sudden," for he was jealous of a newer apprentice. "On September 7th, 1581, Roger went for alltogether from me." But it was not "alltogether," for Roger returned when Dee was old and inform and poor, and remained serving him almost to the end. There was always something patriarchal in Dee's care for the members of his large household, evidenced abundantly in his diary. No doubt their loyalty to him was often severely tried by harsh and cruel outside rumours, but as they knew and loved his real nature they only drew closer towards him.