Edmund, Gloucester's illegitimate son, delivers a soliloquy (a long speech revealing his inner thoughts). He complains to the audience about the way society treats younger brothers and "illegitimate" children. ("Illegitimate" is just a rude way to say that a child is born out of wedlock. Remember, Gloucester told us in act one, scene one that he's not married to Edmund's mom but, he sure had a good time with her.)
Edmund argues that he's just as smart, attractive, and talented as his father's eldest and legitimate son, Edgar.
But because of a technicality of birth, Edgar will get property and an important position and he, Edmund, will get nothing.
We interrupt this program for a history snack: Edmund's beef about the way society treats younger brothers is a reference to primogeniture, the system by which eldest sons inherit all their fathers' wealth, titles, lands, power, debt, etc.
In other words, younger brothers (and all daughters) get shafted. As you can guess, this system tends to create a whole lot of family drama. The same system would have applied to Lear's family if Lear had a son to inherit the crown by lineal succession. Since the king doesn't have a son, he's decided to divvy up the kingdom between his daughters and sons-in-law, as we know. Now, back to our program:
Edmund also insists that, since his parents had such an awesome and "lusty" time in bed when he was conceived, he's far more superior to any person legitimately conceived in a "stale tired bed."
One way or another, Edmund is going to get his brother's land, and we doubt that he's interested in a time share.
Edmund also points out that Gloucester loves him as much as he loves Edgar (but that's not saying much), which seems like evidence that society shouldn't make such a big deal about the difference between "legitimate" and "illegitimate" offspring. Finally, Edmund calls on the gods to "stand up for bastards!" (You know nothing, Jon Snow.)
(Helpful Hint: If you're getting "Edmund" and "Edgar" confused already, here's a tip: Think "G" for good—Edgar is the good brother, and "M" for "malice"—Edmund is the malicious one.)
When Gloucester (Edmund and Edgar's father) comes in, Edmund puts his plan into action. Acting intentionally nervous, he very conspicuously puts away a letter he's supposedly been reading.
When his father asks him what it is, Edmund acts flustered. He hints that the contents of the letter, which is from his brother, are pretty bad and will probably offend Gloucester. Edmund suggests his brother sent the letter as a test.
Gloucester takes the bait and demands to see what the big deal is.
The letter—supposedly from brother Edgar—suggests that the brothers conspire to kill their father. In the letter, "Edgar" claims that obedience to one's elders is a total drag and highly overrated. Plus, by the time Gloucester dies and Edgar (the eldest brother) gets his inheritance, he'll be too old to enjoy it. But, if Edmund (the younger brother) were to help Edgar get rid of their old man, they could both split the profits.
Gloucester, naturally, is shocked and outraged. He asks Edmund how he came upon the letter, and whether this is really Edgar's handwriting.
Edmund, who's beginning to look a lot like an evil genius, says someone threw it in his bedroom window.
It just breaks his heart to have to tell his beloved father that the handwriting is definitely Edgar's.
Edmund then goes on to say that while Edgar never specifically planned a "let's murder-our-father" meeting, he's always running around saying he can't wait for Gloucester to kick the bucket.
Gloucester immediately declares Edgar to be an "unnatural" villain. Edmund, pretending to be the virtuous younger brother, says Gloucester shouldn't jump to any hasty conclusions. Perhaps Edgar wrote this letter to test Edmund's love for their father?
Edmund then promises he can provide his father with some kind of resolution: that very evening, he'll have a conversation with Edgar on which Gloucester can spy. Edmund will talk to Edgar of the business, and Gloucester can form his own conclusion.
While Gloucester is clearly confused and upset by the suggestion that his son Edgar, whom he loves dearly, is a bad guy, he's still up to hearing the proof.
Gloucester then laments that the recent solar and lunar eclipses in Britain are portentous, predicting failed loves, civil wars, treason, mutinies, divided brothers, and even the breaking of bonds between father and son (which is conveniently relevant). As further evidence that something really awful is going to happen, Gloucester points out that Lear has recently had a falling out with his child, Cordelia.
We interrupt this program for another tasty history snack: when Gloucester says the "late eclipses of the sun and moon" are a bad omen, Shakespeare may have had in mind the actual eclipses that were seen in London in October and September of 1605 (about a year before the play's first recorded performance). Just thought you'd like to know, especially since some literary critics point to this as evidence that Shakespeare could not have written King Lear before 1605.
Gloucester worries that they've already seen the best days of their lives, and that only disorder and grief will come with the future.
Gloucester fusses about this mess, reminds Edmund that it's now up to him to sort out Edgar.
He also wonders at the rash banishment of Kent. (All of these issues seem aligned to the prediction of madness and strife.)
After Gloucester exits, Edmund takes time to snicker gleefully about the fact that people are often ready to blame their own failings and circumstances on the stars and their fates, as if they couldn't help being as villainous as they are.
Edmund, who we see is pretty dang self-aware, knows that even if he'd been born during the best zodiacal circumstances, he'd still be a rotten guy.
Then Edgar walks in, a prime opportunity for Part Two of Edmund's plan: Edmund makes a little speech about the horoscope promising death and division that will impact both states and families.
After Edgar teases about how silly horoscopes are, Edmund convinces Edgar that his father is angry at him, and that he should lie low for a while.
Edgar suggests that his father could only think badly of him because some villain has done him wrong, and Edmund agrees that's probably the case, though he stops short of saying, "A-ha! That villain is me!"
Edmund lays it on thick about how Edgar should worry about his enemies, even suggesting Edgar shouldn't go out without a weapon. Edmund also provides a plan, saying if Edgar goes back to his place, he'll drop by and fetch him to speak to their father when the time is right.
Edgar leaves, convinced that Edmund has his best interests in mind. Like his father, Edgar is a gullible guy.
Edmund, alone, crows over how lucky he is to have a brother and father so good that they won't suspect his treachery, simply because they couldn't fathom it. This will make his evil deeds easy. Edmund declares he's sure to get Gloucester's land, if not by rightful inheritance, then by his own wits.