My most heartfelt wishes for your happiness and health in the new year, as well as for that of your dear ones! And my best wishes for the flourishing and completion of the great creation to which you have devoted your mental powers for years and from which the true, scientific philosophy can expect such mighty advancement, indeed its correct and lasting foundation. It was for me an inexpressible joy to find in your new treatise the prospects for your work [on Descriptive Psychology] so close, and to be honest, not only for the expected advancement of our science, but no less for the joyful hope of an essential advance in my own knowledge. Thus I will again feel the great happiness that I so gratefully enjoyed when I was still sitting at your feet: [the happiness] of being enlightened by your clarity, of sharing in the thoughts, projects, and successes of your ever-penetrating mind.
Such pure happiness was also granted me in reading your latest treatise ‘‘On the Origin of Moral Knowledge’’. The foundational thoughts on ethics, contained in the public address itself, were already known to me through your lecture courses. Nevertheless, what a pleasure for me to receive once again these significant, indeed epoch-making, thoughts in concise, sharp, and truly perfected form! Then [there are] the comments. Quite a few students and specialists in law might do without them, while they might prove fatal to some philosophers. (Of course here I mean the longer additions concerning logic). Their magnificent dialectical force, highest critical acuity, extremely careful clarity, and refined tone, filled me with sincere admiration.
By sending me this treatise you have given me great joy. My heartfelt thanks for this. You did me a great service in remembering me so kindly. You will certainly forgive me for expressing my vividly felt gratitude only today once you hear that in the past year, particularly in the summer, I have been doing very poorly. I suffered so much from nervousness that I was not fit for anything and was barely able to prepare my lecture courses. I spent the holidays in the mountains (Tweng, in the Radstädter Tauern), where I gradually recovered. The heavy physical symptoms, such as migraine, weakness etc., diminished, and I returned significantly invigorated. For the past two months my constitution has improved and I now feel completely healthy.
With renewed energy I have taken up again the philosophical investigations regarding the philosophy of mathematics which I had already begun in Vienna, but at that time without even the slightest awareness of the difficulty of the enterprise. Heaven will hopefully allow me to complete the work this winter and hence fill a real and perceptible gap in science. The fact that I was almost entirely unable to build on any useful preparatory research (with the exception of some essential inspirations from your lecture courses in the WS 1885/1886) is probably the main reason that I made progress only laboriously and slowly. I had great difficulties with the full understanding of the logical character of the system of signs of the arithmetica universalis with its negative and imaginary, rational and irrational numbers. The matter is not so simple that everything could be completely settled with the concept of amount and the theory of improper presenting.
Currently I am rethinking my first attempts from the year 1886 regarding the foundations of geometry and the general theory of the continuum. At that time I got stuck because I lacked a true understanding of general arithmetic; now that I have gained clarity in these matters I also hope to overcome the last trace of unclarity regarding the theory of the continuum.
My behavior to this point has demonstrated that the ambition to see my name in print as quickly and as often as possible has not driven me to premature publications. I am certain of your approval in this matter. I will only publish what I deem really useful, whether of a positive or a critical character. Self-criticism is certainly a difficult matter. Hopefully it will not deceive me too much in the very work that is to be adorned with your name, my revered teacher. Well now, I am speaking as though the book already lay wholly or nearly finished before me—and yet there still is so much to create and shape. But I will not despair. I think: not for nothing have I ‘‘long suckled at your sphere’’ – The departure of Stumpf caught me completely off-guard. In him I lose a revered, kind, and benevolent friend, and this pains me. His successor will probably be Erdmann. I’m curious to see how our relationship will develop, after I completely rejected his major work on the axioms of geometry (1877).
But now it is time to come to a close. Please convey my very best regards to your wife. It was a great pleasure for me to hear through Mrs. Löning that she still thinks of me so kindly. Kind regards and best new year’s wishes also to Prof. Marty, who, as is usual at this time, will also now probably be staying with you.
To yourself, my revered teacher, a renewed expression of my ever unchanged and unchangeable reverence, love, and gratitude,