This is the excellent foppery of the world

Draco and Ursa Major, duking it out.

In the long tradition of Shakespearean villains and tricksters spouting truth, King Lear gives us Edmund: Gloucester's bastard son. He's intelligent, sexy, and utterly unscrupulous, believing he deserves no less respect (and money) than his legitimate half-brother Edgar. He succeeds in convincing his father that Edgar wishes to kill him for his lands, betraying Gloucester to Cornwall, and getting named Earl. Though a practicing douche-bag, Edmund is an effective fighter and his ambition gets him far before his fall. 

In the soliloquy I chose, Edmund mocks his father's insistence that the "late eclipses in the sun and moon portend no good to us." Ironically(and as they always do in Shakespeare) the predictions laid out by Gloucester--that love will cool, friendships will fail, brothers will divide, and the King will rail against nature--come true. But that's the beauty of fiction, to write in vague prophecies that match up with real events.

Astrology was the mysterious science of the day, and professional astrologers were hired by the state to serve the kings and queens and provide "wisdom" written in the stars. One of my heroes, Carl Sagan, explained in the documentary series Cosmos thusly:

"Astrology developed into a strange discipline--a mixture of careful observations, mathematics and record-keeping, with fuzzy thinking and pious fraud. Nevertheless, astrology survived and flourished. Why? Because it seems to lend a cosmic significance to the routine of our daily lives. It pretends to satisfy our longing to feel personally connected with the universe. Astrology suggests a dangerous fatalism--if our lives are controlled by a set of traffic signals in the sky, why try to change anything?"

Edmund's speech provides a rant worthy of Sagan's appeal to reason.

King Lear, Act I, Sc. II

Edmund: This is the excellent foppery of the world 

that when we are sick in fortune—

often the surfeit of our own behavior—

we make guilty of our disasters the sun, the moon, and the stars, 

as if we were villains by necessity, 

fools by heavenly compulsion, 

knaves, thieves, and treachers by spherical predominance, 

drunkards, liars, and adulterers by an enforced obedience of planetary influence, 

and all that we are evil in by a divine thrusting-on. 

An admirable evasion of whoremaster man, 

to lay his goatish disposition to the charge of a star! 

My father compounded with my mother under the dragon’s tail 

and my nativity was under Ursa Major, 

so that it follows I am rough and lecherous. 

Fut, I should have been that I am, 

had the maidenliest star in the firmament twinkled on my bastardizing.