Whitman says he doesn't have much faith in talk and "talkers." (You'll notice that the people Whitman criticizes are never named – they are always just some general group.)
Talk is cheap, particularly when people talk about history. He might be referring to religious dogmas about how the world began and how it will end.
For Whitman, all history is the history of the present moment. There is no before or after. The present moment is defined by "the procreant urge of the world." We'll read between the lines for you, he's talking about sex. For Whitman, erotic desire – the desire for new forms and new life – defines the world.
He describes some of the "mysteries" of the world, like the way "opposites" can be "equals." The world is like a well-built house or a well-bred horse.
OK…but what does that really mean? It means the world is not sick or flawed.
Whitman is a raging optimist. For him, it's not a question of whether the glass is half empty or half full: the glass is under a waterfall.
Speaking of water, while the talkers discuss thing like metaphysics and the nature of the spiritual world, Whitman takes a bath.
While "admiring" himself in the bath, he says that every inch of him is beautiful. He seems to be contrasting his view with the Puritan sense of shame in some "dirty" body parts or functions.
Whitman is a healthy guy, and the world seems healthy to him.
He wants to tell his eyes not to look into the future, but instead to figure out ("cipher") himself.