chemical analysis, I heard a student, who was already a practising
physician, state that zinc was an element which contained a great deal
of hydrogen. When the professor attempted to extricate him from his
difficulty, it became apparent that the future doctor had no idea of
what an element was. My classmate, who doubtless entertained as little
liking for chemistry as I did for grammar, had not been able throughout
his entire course to grasp the definition of an element, as I had never
been able to comprehend what a preterite might be.

For my part--and I believe that all of us have had the same experience--
I have never been successful in mastering those subjects which have not
interested me.

Doubtless, also, my mental development has been slow.

As for memory, I have always possessed very little. And liking for
study, none whatever. Sacred history, or any other history, Latin,
French, rhetoric and natural history have interested me not at all. The
only subjects for which I cared somewhat, were geometry and physics.

My college course left me with two or three ideas in my head, whereupon
I applied myself to making ready for my professional career, as one
swallows a bitter dose.

In my novel, _The Tree of Knowledge_, I have drawn a picture of
myself, in which the psychological features remain unchanged, although I
have altered the hero's environment, as well as his family relations,
together with a number of details.

Besides the defects with which I have endowed my hero in this book, I