he petrification of plants, the carbonization
of plants, and then dwelt somewhat on the tendency of certain minerals
to form dendrites, that is, branching {159} processes which look not
unlike plants. He pointed out how easy it is to be deceived by these
appearances, and stated very clearly the distinction between real
plants and such simulated ones.

It will be scarcely necessary for us to apologize for having given so
much space to Stensen's work on geology. Many distinguished
scientists, however, have insisted that no greater advance at the
birth of a science was ever made than that which Stensen accomplished
in his geological work. Hoffman says that after carefully studying the
work, he has come to the conclusion that of the successors of Stensen,
no student of the mountains down to Werner's day had succeeded in
comprehending so many fruitful points of view in geology. None of his
great successors in geology has succeeded in introducing so many new
ideas into the science as the first great observer. For several
centuries most of his successors in geology remained far behind him in
creative genius, and so there is little progress worth while noting in
the knowledge of the method of earth formation, until almost the
beginning of the nineteenth century, though his little book was
written in 1668 and 1669.

Leibnitz regretted very much that Stensen did not complete his work on
geology as he originally intended. Had he succeeded in gathering
together all of his original observations, illustrated by the material
he had collected, his work would have had much greater effect. As it
was, the golden truth which he had expressed in such {160} few words,
without being able always to state just how he had come to his
conclusions, was only of avail to science in a limited way. Men had to
repeat his observations long years afterwards in order to realize the
truth of what he had laid down. Leibnitz considered that it took more
than a century for geological science to reach the point at which it
had been left by Steno's work, and which he had reached at a single
bound. There is scarcely a single modern geologist interested at all
in the history of the science who has not paid a worthy tribute to
Steno's great basic discoveries in the science. It was not a matter
for surprise, then, that the International Congress of Geologists
which met at Bologna in 1881 assembled at his tomb in Florence in
order to do him honor, after the regula