He began spontaneously to consider whether it would be possible to carry out that puerile notion of Rosamond's which had often made him angry, namely, that they should quit Middlemarch without seeing anything beyond that preface.
"Adventurer," by contrast, implies a self-indulgent adrenaline junkie, who scares loved ones by courting puerile risk.
So call me puerile, and unworthy of the pundit's pen for pointing it out, but this is the stuff that revolutions are really made of.