He returned to London and studied medicine with Dr. Blair at St. Bartholomew's Hospital, and astronomy with Dr. Hutton at the Greenwich Observatory. After the decision of the Directors as to his destination, Morrison had most diligently and laboriously pursued the study of Chinese. He learned the Chinese language from a student that he shared lodgings with, called Yong Sam-tak from Canton City. At first they did not get on well together. Morrison absent-mindedly burned a piece of paper with some Chinese characters on it – and infuriated the superstitions of his Chinese mentor, who left for three days. From that time on, Morrison wrote his characters on a piece of tin that could be erased. They continued to work together and studied an early Chinese translation of Gospels named "Evangelia Quatuor Sinice" which was probably written by a Jesuit, as well as a hand-written Latin-Chinese dictionary. Yong Sam-tak eventually joined him in family worship. In this way Morrison made considerable progress in speaking and writing one of the most difficult of languages for an English-speaking person to learn. The hope of the Directors was that, first of all, Morrison would master the ordinary speech of the people, and so be able to compile a dictionary, and perhaps make a translation of the Scriptures for the benefit of all future missionaries. To accomplish this, it was first of all necessary to get a footing on Chinese soil, and not hopelessly offend the Chinese authorities. At this time, dealings of foreigners with the people, except for purposes of trade, was absolutely forbidden. Every foreigner was strictly interrogated on landing as to what his business might be; the price for giving the wrong answers might be unceremonious return on the next vessel. Morrison was aware of the dangers. He traveled to visit his family and bid them farewell in July 1806, preaching 13 times in London, Edinburgh and Glasgow.