Lilly made some progress in astrology under Evans, and practised the art in minor matters with a certain success; but his ambition led him to aspire to the highest place in his profession. He made an experiment to discover a hidden treasure in Westminster Abbey; and, having obtained leave for that purpose from the bishop of Lincoln, dean of Westminster, he resorted to the spot with about thirty persons more, with divining rods. He fixed on the place according to the rules, and began to dig; but he had not proceeded far, before a furious storm came on, and he judged it advisable to "dismiss the demons," and desist. These supernatural assistants, he says, had taken offence at the number and levity of the persons present; and, if he had not left off when he did, he had no doubt that the storm would have grown more and more violent, till the whole structure would have been laid level with the ground. He purchased himself a house to which to retire in 1636 at Hersham near Walton on Thames, having, though originally bred in the lowest obscurity, twice enriched himself in some degree by marriage. He came to London with a view to practise his favourite art in 1641; but, having received a secret monition warning him that he was not yet sufficiently an adept, he retired again into the country for two years, and did not finally commence his career till 1644, when he published a Prophetical Almanac, which he continued to do till about the time of his death. He then immediately began to rise into considerable notice. Mrs. Lisle, the wife of one of the commissioners of the great seal, took to him the urine of Whitlocke, one of the most eminent lawyers of the time, to consult him respecting the health of the party, when he informed the lady that the person would recover from his present disease, but about a month after would be very dangerously ill of a surfeit, which accordingly happened. He was protected by the great Selden, who interested himself in his favour; and he tells us that Lenthal, speaker of the house of commons, was at all times his friend. He further says of himself that he was originally partial to king Charles and to monarchy: but, when the parliament had apparently the upper hand, he had the skill to play his cards accordingly, and secured his favour with the ruling powers. Whitlocke, in his Memorials of Affairs in his Own Times, takes repeated notice of him, says that, meeting him in the street in the spring of 1645, he enquired of Lilly as to what was likely speedily to happen, who predicted to him the battle of Naseby, and notes in 1648 that some of his prognostications "fell out very strangely, particularly as to the king's fall from his horse about this time." Lilly applied to Whitlocke in favour of his rival, Wharton, the astrologer, and his prayer was granted, and again in behalf of Oughtred, the celebrated mathematician.