The heart knoweth his own bitterness; and a stranger doth not intermeddle with his joy.
– Proverbs 14:10
[T]his proverb does not contrast bitterness and joy, but treats them both alike as unknowable to a stranger, or another person. It is a wise observation that a person knows his own deep sorrows and profound joys. These cannot be fully expressed to or known by another. Wisdom would mean being careful to speak into someone’s joy or pain, or assuming you fully understand it. We do have comfort in suffering knowing that God sees and understands (1 John 3:20; Hebrews 2:18; 4:15).