2 vol., 4to, deckled edges, publisher's gray paper boards with title impressed in gilt, in publisher's gray slipcase.  272-[2], [4]-275/550 pp. In fine condition, with a few slightly unevenly bound pages in vol. I between p. 206 - 222.  First edition of this fine two-volume publication containing a rich bibliographical and iconographical index and a list of the master's students, illustrated with a section of 77 reproduction photographs included in the pagination. Copy XII of only 50 deluxe copies printed in large format on laid Ingres d'Arches paper, containing one inserted additional plate 'hors texte' and an additional 6 pp. booklet of "illustrations hors-serie." This copy inscribed on the ffe of Volume I by the son of the composer/violinist Antoine Ysaye to Belgian man of letters Robert De Smet, and also including an important and lengthy original autograph letter from Eugene Ysaye addressed to his wife Louise (also called "Michette"), the letter transcribed in full within the printed volume on pages 170-172.  Aix-les-Bains, 06.11.1908, 16 pp. 4 Double ff., 12mo, on monogram letterhead of the Avenue Brugman address. An important letter in which the virtuoso makes a comparison between the painter and musician, expresses poetically his feeling for nature and reports his philosophy of life and death: "(...) we must give ourselves over to the laws of nature of which we are only one atom and, always ascending towards our sources, - to God! - we must and we want to lift up our souls, which finally, perfect, white, and immaculate, are the only gift that God accepts." 

Translated from the French, the letter in full:

"Dear Michette, (henceforth to be known as Louise)

It is not yet eight in the morning and here I am, pen in hand, thinking of answers for you, reading over the spirit and the letter of your last two letters, quite dissimilar, mixing wheat and chaff, gold and zinc, ivory and ebony.

I look outside: the weather is radiant, its clarity triumphs over the clouds and it seems that, from my window, I could reach out and touch the mountain opposite, with its peak gloriously pointing to the sky, which it seems to reach!

Bringing my gaze to the large trees in the garden, I caress with my eyes the greenery where the dew has left its soft luster; I see the light: blue, gray, green on a sparkling silver background ...

Happy are the painters who can analyze, better than musicians, the composition of the air, the details of vegetation and the thousands of nothings which adorn the trees and flora. But the musician gains something just from watching, almost without seeing anything; his eye is listening - so to speak - to vibrant and rich harmonies.

But what can one say of this powerful creation: Nature! Ah! To understand this divine harmony, this supreme music! To feel oneself soften while watching a leaf move under the caress of a warm wind; to be moved, charmed by the ineffable singing of this little winged creature who balances on a branch and, without ever stopping, always with enough breath, without professional fatigue (!) rolls out garlands of trills and flying arpeggios, and the most harmonious chirping (I almost said harmonic because the more I listen, the more I perceive music in this tangle of incomparably pure high notes.)

I thought a moment ago that birdsong is the adornment of trees, as wild flowers, humble and frail, adorn the meadows. What to say then in the face of the work of God or Nature (is not it the same thing?), about these giants that rise skyward, over there in the distance! What to say about the air, the wind, the continuous work of the earth, which bends man under its secrets, under its works, all beautiful, all useful, waking in the artist the desire of creation.

Well, if I understand and pray before this 'great all,' have I not done even better than admiring a painting or a symphony? Here, on the other hand, I do not enjoy one feeling, of one beauty, I enjoy a thousand sensations, of all the beauties which truths congregate about.

To understand and love 'nature' is to be 'natural.' It is to think and believe that in our short life (or short death) we need not defend ourselves for existing. Like humble flowers, we must abandon ourselves to the laws of nature, of which we are only one atom, and, always ascending towards our origins, to God, we must and will raise our soul, which finally, perfect, white, immaculate, is the only gift God accepts.

These are thoughts expressed as best I can, because if the nightingales lent me their chatter for a moment, I would be willing to admit that I did not know how to make the delicious song that they make themselves. Yet if you find some pleasure in hearing me, I will be delighted because, in sweetness, I have led you to understand that there is more happiness than pain in this passage from life to death: that rain is a necessity, just as the night makes one appreciate the day. To those who know how to see in contrasts the signs of harmony, order, perfection, should not a smile always be reserved, to find the force of resistance in patience and in the hope of happiness?

Let us love and forgive; we are not the judgers, but those who will be judged. Thus, mercy and the remission of sins impose themselves on all; thus, sacrifice is sweet, when it provides for the work of goodness.

Our fate is the sweetest thing we have, because we do not suffer the great cruelties which afflict many others.

Know how to separate the wheat from the chaff, the gold from the less precious metals which surround you. Be good, you for whom it is so easy to be good, and the sky, the flowers, the nightingales, art and all of nature will love you and celebrate you as I love you and celebrate you.

Eugène."