When a face is sad a heart may be HAPPY?

[TonyChanYT]

Ecclesiastes 7 contains a set of philosophical paradoxes to get the readers to think deeper than the surface meanings, e.g., verse 2:

It is better to go to a house of mourning
Than to go to a house of feasting,
Because that is the end of every person,
And the living takes it to heart.

Mourning is better than feasting because in the end, everyone dies and people mourn his death.

This is reinforced in verse 3:

Sorrow is better than laughter,
For when a face is sad
a heart may be happy.

Sorrow is compared to mourning. Laughter is compared to feasting. When one hides his sadness, it causes internal turmoil. When one mourns and shows his sorrow, it heals the heart internally. It serves a cathartic release function. It calms the conscience. It is the smart and wise thing to do.

4 The mind of the wise is in the house of mourning,
While the mind of fools is in the house of pleasure.

Fools hide their hurts in pleasure. Smart people are not afraid to show mourning for it.

When a face is sad a heart may be happy. How?

Your heart is sad. You show the mourning on your face. Crying is a cathartic release. You let go of the heartache.