==What does this mean?== 

 :In an age when a man's stature was measured not merely by the "cut of his breeches," but by his riding, Gibbon was a lonely figure. 

 I do not consider myself to be a stupid person, but the above makes little sense to me. I can only imagine it is a euphemistic way of saying that in Gibbon's day (as now?) a man's genitals were liable to being scrutinised even while he was fully dressed and that his were presented an unusual sight. It is a wonderful sentence, almost worthy of the man himself, but perhaps a trifle too elliptical for its present setting.