In "The Fall of the House of Usher," what were Roderick's motives for burying Madeline alive when it seems that they had a close...

You have asked a great question that really goes to the
heart of this tale. We are never clear whether Roderick knowingly buries his sister
alive out of pure malicious evil or whether it is just a mistake that he makes because
of the curse that is upon the House of Usher. Consider what the narrator says as they
look upon Madeline's face one last time before entombing
her:

The
disease which had thus entombed the lady in the maturity of youth, had left, as usual in
all maladies of a strictly cataleptical character, the mockery of a faint blush upon the
bosom and the face, and that suspiciously lingering smile upon the lip which is so
terrible in death.

What is
interesting is that the nature of Madeline's appearance accords exactly with the
symptoms of her disease, illnesses of a "cataleptical character," and it is the narrator
that reports this to us first hand. Although we are told at the conclusion of the story
that Roderick "heard" her first movements in the coffin, we could perhaps excuse him for
thinking this was just his fancy.

However, we are never
precisely sure if Roderick buried her deliberately or if he can be excused because of
his illness and the way that if effects his senses and the nature of her illness that
does, we are told, give her an appearance of death.