WW describes his encounters with the mountains and lakes of Scotland. Travelling alone helps him speculate. In his history of the inductive sciences ['The History of the Inductive Sciences, from the Earliest to the Present Time', 3 vols., 1837] he will 'give a history of some of the principal sceinces, making the epochs when the great steps were made, the preludes, and the sequels of these epochs, the way in which each was essential to the next and so on'. WW hopes this will be followed by showing 'that in all great inductive steps the type of the process has been the same. And I have in the Second Book ['The Philosophy of the Inductive Sciences, Founded upon their History', 2 vols., 1840] to explain what facts this process consists of, what conditions it requires, what faculties it calls into play. I expect to show clearly that in order to arrive at knowledge or science we must have, besides impressions of sense, certain mental bonds of connexion, ideal relations, combinatory modes of conception, sciential conditions, or whatever else you can help me call them: they are what I call ideas in my former letter' [see WW to RJ, 5 August 1834]. Thus space is the ideal relation on which the science of geometry depends; time, cause, likeness, substance, life, are ideal relations on which other sciences depend. Now when I have shown distinctly how these ideal relations are the conditions of physical sciences which have already made a general acknowledged progress, I shall have to try to discover the nature of the analogy which exists between these sciences, and our knowledge respecting morals, taste, politics, language, and generally all hyperphysical knowledge'. WW's philosophy also points out 'the nature of each of the inductive steps of which the progress of physical science has consisted, under what conditions it could be and was made, and especially how it rendered the next step possible by its influence on current ideas and on language. Now I shall want to do the same thing with regard to some of the hyperphysical sciences, and thus shall have to give a criticism of their past history fashioned upon a general type'.