Humphrey shows in his writings that he had read deeply; Homer and Aristotle and Plato are quoted in his Discourse to prove a north-west passage to Cathay. Philosophers of Florence, Grantor the Grecian, and Strabo, Proclus, and Philo in his book _de Mundo_, and the German Simon Gryneus, and a host of modern geographers are called to bear witness to his theory that America was an island. Then he had read all the accounts brought home by great seamen, and skilfully wrought them together to prove his theory. But of course his facts were very unreliable and mixed with strange errors, but that was not his fault. If he believed that there was unbroken land to the South Pole, except for the narrow opening of the Straits of Magellan, the error was not his. At the end of his memorial to the Queen, he writes: "Never therefore mislike with me for the taking in hand of any laudable and honest enterprise; for if through pleasure or idleness we purchase shame, the pleasure vanisheth, but the shame remaineth for ever. Give me leave therefore, without offence, always to live and die in this mind: that he is not worthy to live at all that, for fear or danger of death, shunneth his country's service and his own honour, seeing that death is inevitable and the fame of virtue immortal." We can imagine the great Queen looking admiringly at this tall knight of Devon, so fair and yet so strong, so practical and inventive, and yet so compact of fancy and imagination; a man after her own heart, brave and loyal, and one who feared God alone. Humphrey was only twenty-five years old when he petitioned the Queen in association with Anthony Jenkinson for licence to find out a north-eastern passage to Cathay, a country which surpassed in wealth all the parts of the Indies visited by the Spaniards. Gilbert promised to fit out such an expedition at his own expense, all the profits to go to those who embarked upon it, except the fifths, which belonged to the Crown. However, Elizabeth did not yet listen favourably to this project; she sent Jenkinson back to Russia as her Ambassador, and found service for Gilbert under the Earl of Warwick at Havre in 1563. Here he received a wound and had to come home for a space of three years; then he was ordered to Ireland in July 1566, to be employed under the Lord Deputy, Sir Henry Sidney. Humphrey was appointed captain in the army which under Sidney was resisting the forces of the Irish rebel chief, Shan O'Neill, and saw a good deal of desperate fighting.