ounded, Virchow then propounded to us, his disciples, with such
incisive assurance that every one of us was convinced of their truth;
and yet later experience has shown that they were in part
insufficiently proved and in part wholly false. For example, I will
only here recall his famous theory of the connective-tissue, for which
I myself in several of my early works (1856 to 1858) broke a lance.
His theory seemed to explain a host of the most important
physiological and pathological phenomena in the simplest manner, and
yet it was afterwards proved to be false. In spite of this, I declare
to this day that it was of the greatest service for the development of
our acquaintance with the formation of the connective-tissue; as a
guiding hypothesis and as a provisional clue to our investigations.
Virchow, on the contrary, if he impartially reflects on the part he
took in the diffusion of this misleading doctrine, must reproach
himself severely for it. For "we must draw a hard and fast line
between what we are to teach and what we are to investigate. What we
investigate are problems," but "the problem ought not to be the
subject of teaching." That Virchow, in his course of instruction,
every day belied this, his present view of teaching, that he every
hour taught his disciples some unproved theory and problematical
hypothesis, every one knows who, like myself, for years and with the
deepest interest, enjoyed his distinguished instruction. Still the
captivating charm of this instruction--in spite of the defective
method of unprepared lectures--lay precisely in this, that Virchow as
a teacher constantly let us, his pupils, enter into those problems
with which he himself at the moment was occupied; that he propounded
to us his personal hypothesis for the elucidation of the given facts.
And what really gifted teacher who lives in his science would not do
the same? Where is there, or where has there ever been, a great master
who in his teaching has confined himself to only imparting certain
and undoubtedly ascertained facts? Who has not, on the contrary, found
that the charm and value of his instruction lay precisely in
propounding the problems which link themselves with those facts, and
in teaching the uncertain theories and fluctuating hypotheses which
may serve to solve these problems? Or is there for the young and
struggling mind anything better, or more conducive to culture, than to
exercise the intelligence in problems of inve