Roger Bacon was the child of royalist parents who were driven into exile and reduced to poverty by the civil wars. From Oxford, where he studied under Edmund of Abingdon to whom he owed his introduction to the works of Aristotle, he passed to the University of Paris, and spent his whole heritage there in costly studies and experiments. "From my youth up," he writes, "I have laboured at the sciences and tongues. I have sought the friendship of all men among the Latins who had any reputation for knowledge. I have caused youths to be instructed in languages, geometry, arithmetic, the construction of tables and instruments, and many needful things besides." The difficulties in the way of such studies as he had resolved to pursue were immense. He was without instruments or means of experiment. "Without mathematical instruments no science can be mastered," he complains afterwards, "and these instruments are not to be found among the Latins, nor could they be made for two or three hundred pounds. Besides, better tables are indispensably necessary, tables on which the motions of the heavens are certified from the beginning to the end of the world without daily labour, but these tables are worth a king's ransom and could not be made without a vast expense. I have often attempted the composition of such tables, but could not finish them through failure of means and the folly of those whom I had to employ." Books were difficult and sometimes even impossible to procure. "The scientific works of Aristotle, of Avicenna, of Seneca, of Cicero, and other ancients cannot be had without great cost; their principal works have not been translated into Latin, and copies of others are not to be found in ordinary libraries or elsewhere. The admirable books of Cicero de Republica are not to be found anywhere, so far as I can hear, though I have made anxious enquiry for them in different parts of the world, and by various messengers. I could never find the works of Seneca, though I made diligent search for them during twenty years and more. And so it is with many more most useful books connected with the science of morals." It is only words like these of his own that bring home to us the keen thirst for knowledge, the patience, the energy of Roger Bacon. He returned as a teacher to Oxford, and a touching record of his devotion to those whom he taught remains in the story of John of London, a boy of fifteen, whose ability raised him above the general level of his pupils. "When he came to me as a poor boy," says Bacon in recommending him to the Pope, "I caused him to be nurtured and instructed for the love of God, especially since for aptitude and innocence I have never found so towardly a youth. Five or six years ago I caused him to be taught in languages, mathematics, and optics, and I have gratuitously instructed him with my own lips since the time that I received your mandate. There is no one at Paris who knows so much of the root of