On the three easier responses
“I have striven not to laugh at human actions, not to weep at them, nor to hate them, but to understand them.”
Note that he lists three, not one. Mockery, grief and hatred are different reactions to the same difficulty, and all three are ways of settling the matter without having to look further.
Understanding is slower and less satisfying, and Spinoza chooses the verb striven rather than claiming he manages it. He was writing about politics, where the temptation to take one of the first three is strongest and the cost of doing so is highest.