The supplements to this Fourth Book would be considerable indeed if I had not, on the occasion of the prize questions set by two Scandinavian Academies, already written detailed monographs on two of its most vital and principal topics, namely freedom of the will and the foundations of morality. These were published in 1841 under the title The Two Fundamental Problems of Ethics. It is therefore just as vitally necessary that my readers be familiar with this work as was the case with the supplement to the Second Book, which presupposed a familiarity with On Will in Nature. In general I require that anyone who wants to be acquainted with my philosophy must read every line I have written. I am not prolific, I do not strive to earn honoraria, nor am I in the business of churning out compendia. My goal is not to meet with ministerial approval – in short, I am not the sort of person whose pen is swayed by personal ambition: I strive only for truth, and I write as the ancients wrote, with the sole intention of preserving my thoughts so that they can someday benefit those who understand how to think about them and to value them. This is why I have not written very much, but this little with care and over long intervals. I have also confined to a minimum the sometimes unavoidable repetitions one finds in philosophical works due to their interconnections (not a single philosopher can avoid these entirely), so that the vast majority is found in only one place. This is why anyone who wishes to learn from me and understand me should not leave anything that I have written unread. Of course people can judge and criticize me without having done this, as experience has shown; and I wish them every happiness.

Meanwhile, we welcome the extra space won for this fourth supplementary Book through the elimination of two main topics. For since the insights that lie closest to everyone's heart and are thus the tip of the pyramid of any system, its final results, are concentrated in my final Book as well, we will be glad to allow greater scope for any more solid grounding or precise explanation of them.