Lines 365-385: Why are there public demonstrations taking place?

According to King, public demonstrations are taking place in order that the "negro" might release repressed emotions.

The Negro has many pent-up resentments and latent frustrations, and he must release them. So let him march; let him make prayer pilgrimages to the city hall; let him go on freedom rides--and try to understand why he must do so. If his repressed emotions are not released in nonviolent ways, they will seek expression through violence; this is not a threat but a fact of history.