I am giving this book to the Public with great reluctance. Though I have had it in mind for many years and have put no end of thought and work into it, it seems to me inadequate and unsatisfactory. It will hardly be published before I shall discover in it errors both of omission and commission. The book presents a new definition of principles, a new association of ideas. It is inconceivable that this, my first published statement, should be either consistent or complete. It will be a long time, I am sure, before it can be brought to a satisfactory shape. It is simply the best statement that I can make at this time. One reason, perhaps my best reason, for publishing this Theory, before it is completely worked out.