For the prophet Isaiah, "that day" is the day of the Lord, when God will manifest His presence and His power. The day on which a person finds himself face to face with God, if he does not hide from Him. But for us such a day has already come! God accomplished His salvation through the Son, who is with us all the days; He sent the Spirit, the Comforter, who fills our hearts with fearlessness, strength, and songs of praise. This means that for us every day is the day of the Lord, and today is too. Are we trying to hide?