In paragraphs 3, 4, and 5 of the passage, the writer of the Declaration makes the

Douglass wishes he could write a speech about how easy and delightful life is, but his life and all other african americans' in america has been hard, cruel and miserable. so he gives a speech about truth, how difficult it is to find a glimmer of light in the misery and darkness of slavery. if he were to write an easy and delightful speech, there wouldn't be a point, because at that time african americans were prejudiced against extremely strong and beaten down and treated like animals.  if douglass were to write an easy and delightful speech, it would be about how his brothers and sisters had risen out of slavery and treated as equals; but they're not, so he can't.