xvi PREFACE
lunacy. I f one of the sanest of poets, Wordsworth had, as he said, not unfrequently to exert strength, as by shaking a gate-post, to gain assurance that the world around him was a reality, his mind could not at those times have been wholly sane. Sanity is difficult to define, except negatively ; but, even though we may be convinced of the truths of the mystic, that nothing is what it seems to be, the above-mentioned conduct suggests temporary insanity. It is sufficient to conclude, as any Philistine would, that whoever has to shake a gate-post to convince himself that it is not a vision is dangerously near madness. Mad people do such things; those who carry on the work of the world as useful and law-abiding citizens do not. I may add that I myself had the privilege of hearing at first hand the narrator's own account of this incident, which was much emphasized by his gestures and tones. Wordsworth's unexpected sally was in reply to a timid question by the late Professor Bonamy Price, then a young man, concerning the exact meaning of the lines in his famous "Ode to Immortality," " not for these I raise the song of praise ; but for those obstinate questionings of sense and outward things," etc.
I cannot speak from the present returns, but only from my own private knowledge of the somewhat abnormal frequency with which eccentricity, or other mental unsoundness, occurs in the families of very able scientific men. Lombroso, as is well known, strongly asserted the truth of this fact, but more strongly, as it seems to myself, than the evidence warrants.
