I came across this curious tidbit the other day; this is Johnathan Edwards, addressing the question of whether the Christians in heaven will not be saddened by the eternal sufferings of the damned. The source is here.

The seeing of the calamities of others tends to heighten the sense of our own enjoyments. When the saints in glory, therefore, shall see the doleful state of the damned, how will this heighten their sense of the blessedness of their own state... When they shall see how miserable others of their fellow-creatures are...when they shall see the smoke of their torment...and hear their dolorous shrieks and cries, and consider that they in the mean time are in the most blissful state, and shall surely be in it to all eternity: how they will rejoice!