“I stayed at Cambridge during part of the winter vacation, and to avoid expense I quitted my lodgings and went for a time into somebody’s rooms in the Bishop’s Hostel. (It is customary for the tutors to place students in rooms when their right owners are absent.) I took with me Thucydides and all relating to it, and read the book, upon which the next term’s lectures were to be founded, very carefully.  The latter part of the vacation I spent at Bury, where I began with the assistance of my sister to pick up a little French:  as I perceived that it was absolutely necessary for enabling me to read modern mathematics.

“During a part of the time I employed myself in writing out a paper on the geometrical interpretation of the algebraical expression sqrt(-1).  I think that the original suggestion of perpendicular line came from some book (I do not remember clearly), and I worked it out in several instances pretty well, especially in De Moivre’s Theorem.  I had spoken of it in the preceding term to Mr Peacock and he encouraged me to work it out.  The date at the end is 1820, January 21.  When some time afterwards I spoke of it to Mr Hustler, he disapproved of my employing my time on such speculations.  About the last day of January I returned to Cambridge, taking up my abode in my former lodgings.  I shewed my paper on sqrt(-1) to Mr Peacock, who was much pleased with it and shewed it to Mr Whewell and others.

“On February 1 I commenced two excellent customs.  The first was that I always had upon my table a quire of large-sized scribbling-paper sewn together:  and upon this paper everything was entered:  translations into Latin and out of Greek, mathematical problems, memoranda of every kind (the latter transferred when necessary to the subsequent pages), and generally with the date of the day.  This is a most valuable custom.  The other was this:  as I perceived that to write Latin prose well would be useful to me, I wrote a translation of English into Latin every day.  However much pressed I might be with other business, I endeavoured to write at least three or four words, but if possible I wrote a good many sentences.

“I may fix upon this as the time when my daily habits were settled in the form in which they continued for several years.  I rose in time for the chapel service at 7.  It was the College regulation that every student should attend Chapel four mornings and four evenings (Sunday being one of each) in every week:  and in this I never failed.  After chapel service I came to my lodgings and breakfasted.  At 9 I went to College lectures, which lasted to 11.  Most of my contemporaries, being intended for the Church, attended also divinity lectures:  but I never did.  I then returned, put my lecture notes in order, wrote my piece of Latin prose, and then employed myself on the subject which I was reading for the time:  usually taking mathematics at this hour.  At 2 or a little sooner I went out for a long walk, usually 4 or 5 miles into the country:  sometimes if I found companions I rowed on the Cam (a practice acquired rather later).  A little before 4 I returned, and at 4 went to College Hall.  After dinner I lounged till evening chapel time, 1/2 past 5, and returning about 6 I then had tea.  Then I read quietly, usually a classical subject, till 11; and I never, even in the times when I might seem most severely pressed, sat up later.