Exile in Paris meant friendly intercourse with, and consolation of the Queen, but also scientific research. In 1651 Evelyn was visiting him there, and being stirred by his enthusiasm into attending Febur's chemistry lectures along with him. Before that must have taken place his pilgrimage to Descartes, who died in 1650. Apparently Sir Kenelm had gone to Egmont as an unknown stranger; and it throws light on his wide reputation as a man of ideas and a conversationalist, that into his torrent of questions and speculation Descartes broke with, "You can be none other than Digby." The English scientist's practical mind--for he had always a practical end in view, however fantastic his methods--showed itself in his counsel to the author of the _Discours sur la Methode_. Why all this labour for mere abstract speculation? Why not apply his genius to the one great subject, the prolongation of human life? Descartes, it appears, did not need the advice. He said the subject was engaging his mind; and though he "dared not look forward to man being rendered immortal, he was quite certain his length of life could be made equal to the patriarch's." In fact, he was composing at the time an _Abrege de Medecine_, and popular report said he believed men could live four or five hundred years. He died prematurely of too much faith in his own medical theories. In 1653 permission was given to Digby to return, on condition he would not meddle with Royalist plots. He had been in communication with Cromwell, and had done some diplomatic business for him in Paris. On his return in 1654, and for the next few years, he was in the closest relations with the Protector, thereby carrying out the principle he had probably adopted from White, of a "universal passive obedience to any species of government that had obtained an establishment." His Royalist friends made an outcry, and so did the Puritans; but Digby was confident of obtaining from Cromwell great advantages for the English Catholics, and the Protector, it seems, fully trusted the intentions and the abilities of this strange and fascinating personality who came to him out of the enemy's camp. Delicate business was given into his hands, that of preventing an alliance between France and Spain. Prynne, in his _True and Perfect Narrative_, bitterly denounced Cromwell in "that Sir Kenelme Digby was his particular favourite, and lodged at Whitehall; that Maurice Conry, Provincial of the Franciscans in England, and other priests, had his protections under hand and seal." Of Digby's feelings towards Cromwell there is clear evidence. It seems his loyalty had been questioned in his absence; and he writes from Paris, in March, 1656, to Secretary Thurloe: "Whatsoever may be disliked by my Lord Protector and the Council of State must be detested by me. My obligations to his Highness are so great, etc." And again, "How passionate I am for his service and for his honour and interest, even to exposing my life for