last thirty years, in the most absolute retirement and the completest
silence.

Moreover, it was not unimportant to warn the public against the errors,
exaggerations, and legends which have collected about my person, and thus
to set all things in their true light.

In undertaking this task my devoted disciple has to some extent been able
to replace those "Memoirs" which he suggested that I should write, and
which only my bad health has prevented me from undertaking; for I feel that
henceforth I am done with wide horizons and "far-reaching thoughts."

And yet on reading now the old letters which he has exhumed from a mass of
old yellow papers, and which he has presented and co-ordinated with so
pious a care, it seems to me that in the depths of my being I can still
feel rising in me all the fever of my early years, all the enthusiasm of
long ago, and that I should still be no less ardent a worker were not the
weakness of my eyes and the failure of my strength to-day an insurmountable
obstacle.

Thoroughly grasping the fact that one cannot write a biography without
entering into the sphere of those ideas which alone make a life
interesting, he has revived around me that world which I have so long
contemplated, and summarized in a striking epitome, and as a strict
interpreter, my methods (which are, as will be seen, within the reach of
all), my ideas, and the whole body of my works and discoveries; and despite
the obvious difficulty which such an attempt would appear to present, he
has succeeded most wonderfully in achieving the most lucid, complete, and
vital exposition of these matters that I could possibly have wished.