Oxford had enjoyed an influx of scientific inquiry and humanism – Roger Bacon (1220-92), John Wycliffe (1330-84), Desiderius Erasmus (1469-1536) and Sir Thomas More (1477-1535), all had their influence on the colleges. The present head of Christ Church for Locke was the Presbyterian John Owen (1616-83), a Puritan proponent of toleration and independence for Protestant sects and an earlier supporter and follower of Oliver Cromwell (1599-1658). (Owen travelled with Cromwell into his wars in Scotland and Ireland). Avoiding a career in theology and despising the dry Scholasticism (although the techniques and knowledge were of great use to his mind), Locke concentrated his studies on medical science at Oxford and later held teaching and diplomatic positions until meeting up with Lord Ashley Cooper in 1666 (later Earl of Shaftesbury). The position of a don was Locke’s preferred ambition and would have loved to live his whole life at Oxford – but events altered this path and he was illegally ejected on political grounds in 1684 from his studentship at Christ Church.
There were immediate responses from the High Church Anglican clergy, published by Thomas Long and Jonas Proast . Long believed the letter was written by an atheistically disguised Jesuit plot for the Roman Catholic Church to gain dominance by bringing chaos and ruin to church and state. Proast attacked the Letter and defended the view that the government has the right to use force to cause dissenters to reflect on the merits of Anglicanism, the True Religion. Locke's reply to Proast developed into an extended, controversial exchange.
An Essay Concerning Human Understanding begins with a short epistle to the reader and a general introduction to the work as a whole. Following this introductory material, the Essay is divided into four parts, which are designated as books. Book I has to do with the subject of innate ideas. This topic was especially important for Locke since the belief in innate ideas was fairly common among the scholars of his day. The belief was as old as the dialogues of Plato, in which the doctrine of a world of ideas or universals had been expressed. Plato had taught that ideas are latent in the human mind and need only the stimulation of sense perception to bring them to the level of consciousness. Many of the philosophers of the so-called rationalistic school followed Plato in this respect.