This quotation is from the fifth act of "Hamlet." The Queen, Hamlet's mother, has drunk the poison and dies. Her death is avenged by Hamlet as he kills the king. He has also been poisoned by the tip of Laertes' sword. He pours the poisoned wine down the King's throat and speaks these lines to Horatio.
"O proud death,
What feast is toward in thine eternal cell,
That thou so many princes at a shot
So bloodily hast, struck?" Hamlet. Act V. Sc. 2. L. 375.
Horatio follows up this quote with the famous quotation, "Good night sweet Prince."
The play begins with Hamlet lamenting the death of his father by the hand of his uncle, Claudius. The play ends with death coming full circle. Polonis, Claudius, Laertes, Gertrude, Ophelia, and Hamlet all die.
"Pysical disease as manifestation of spiritual corruption. Evil has finally claimed everyone except Horatio (whom Hamlet barely prevents from committing suicide with the poisoned cup) and Fortinbras."