The slight alterations made, the adaptation of the text to the eye, detract nothing from the original freshness of the work.
In a letter to one of the editors, Osler described these lectures as "an aeroplane flight over the progress of medicine through the ages." They are, in effect, a sweeping panoramic survey of the whole vast field, covering wide areas at a rapid pace, yet with an extraordinary variety of detail.

The slow, painful character of the evolution of medicine from the fearsome, superstitious mental complex of primitive man, with his amulets, healing gods and disease demons, to the ideal of a clear-eyed rationalism is traced with faith and a serene sense of continuity.

The author saw clearly and felt deeply that the men who have made an idea or discovery viable and valuable to humanity are the deserving men; he has made the great names shine out, without any depreciation of the important work of lesser men and without cluttering up his narrative with the tedious prehistory of great discoveries or with shrill claims to priority.

Of his skill in differentiating the sundry "strains" of medicine, there is specific witness in each section.

Osler's wide culture and control of the best available literature of his subject permitted him to range the ampler aether of Greek medicine or the earth-fettered schools of today with equal mastery; there is no quickset of pedantry between the author and the reader.