Isaiah finds himself in the presence of the living God—the Holy One. This is a terrifying situation because Isaiah knows full well that the unholy cannot endure the presence of the Holy.
The miraculous catch of fish happens not just once in the ministry of Jesus but twice. And, interestingly this miracle happens twice to the same person. Simon Peter.
Paul imagines a time when we are no longer immature children, seeking to show off spiritually, but instead demonstrating the maturity that comes from edifying others.
Thus, the people weep and mourn, but they are told to cease with their mourning and rejoice and celebrate as a festival without worry or care, for the day is holy to the LORD who is their refuge and strength.