He lived during the night.

Don Marcelo, upon investigating the artist's work, could not contain his indignation.

Every morning the two Desnoyers were accustomed to greet the first hours of dawn--the father leaping from his bed, the son, on his way home to his studio to throw himself upon his couch not to wake till midday.
The credulous Dona Luisa would invent the most absurd explanations to defend her son.

Who could tell?
Perhaps he had the habit of painting during the night, utilizing it for original work.

Men resort to so many devilish things!.