He can't even realize the seriousness of what he did!
In autumn he gave himself up to hunting with the same business-like seriousness--leaving home for a month, or even two, with his hunt.
But then the seriousness of the matter began to sink in.
In spite of the seriousness of the situation, Dean was forced to stifle a chuckle.
In his later years he overcame the drunkenness that was habitual to him in youth; he developed seriousness of character and unselfish devotion to what lie believed was the cause of patriotism; and he won the respect of men of high character and capacity in France and Holland.