A theef he was for sothe of corn and mele, And that a sly, and usuant for to stele. (85 – 86)
This passage helps establish the sneakiness of Symkyn's character by showing that he's a total cheat. The dishonest miller is always cheating his poor customers out of corn. Later in the story, we learn his method: he "pads" the customers' sacks of wheat flour with bran flour, a less expensive substance, thus keeping the wheat flour (and the increased profit) for himself. By saying that Symkyn is "sly," or sneaky, this passage implies that he rarely gets caught, so well does he conceal his deceit from his customers. He may have learned the skill of cheating through long experience, since he's "usuant for to stele," implying that he does so often.
For hooly chirches good moot been despended On hooly chirches blood, that is descended. Therfore he wolde his hooly blood honoure Though that he hooly chirche sholde devoure. (129 – 132)
This passage, which discusses the inheritance Symkyn's daughter, Malyne, is likely to get from her grandfather, the parson, is an example of medieval anticlericalism. Anticlericalism was a collection of negative attitudes and stereotypes about clergy members which grew out of resentment of the clergy's misuse of their powers. This passage highlights one such misuse: it implies that Malyne's grandfather, the parson, is stealing the Church's property (perhaps in the form of collections from parishioners). This property, which should be held in common by the Church, will instead be used by him to advance himself and his own heirs. The other bit of anticlericalism contained in this passage is the fact that the Parson has a granddaughter at all. As a clergy member, he's supposed to be chaste, but he has obviously had a sexual liaison that resulted in a child, Symkyn's wife.
Sik lay the maunciple on a maladye; Men wenden wisly that he sholde dye. For which this millere stal bothe mele and corn And hundred tyme moore than biforn; For therbiforn he stal but curteisly, But now he was a theef outrageously. (139 – 144)
Symkyn's sin of stealing is compounded by the fact that here, he takes advantage of the lenience of a man on his deathbed. The humor of this passage is contained in the line implying that the miller stole "curteisly" (politely) before, whereas now he steals "outrageously." For how is it possible to "politely" steal from someone?
But now he was a theef outrageously, For which the wardeyn chidde and made fare. But therof sette the millere nat a tare; He cracketh boost, and swoor it was nat so. (144 – 147)
Symkyn has already committed the sin of stealing from a man on his deathbed, and now he adds another sin by lying about it. He denies any wrongdoing when the manciple (or purchaser) for the university confronts him about the missing corn. This passage contains a bit of ambiguity in the way it fails to specify whether the manciple is angry about the stealing, or about the "outrageousness" of it. Could it be that, in the past, the manciple simply put up with Symkyn's dishonesty but that now, finally, he has gone too far?
And hardily they dorste leye hir nekke The millere sholde not stele hem half a pekke Of corn by sleighte, ne by force hem reve. (155 – 157)
Aleyn and John promise to make sure the Miller doesn't steal corn from the university if they are allowed to go to the mill themselves. By laying "hir nekke" that the miller won't steal from them, these two also lay their reputation on the line. You can imagine the two boasting to their dorm-mates about their superior ability to spot deception; the stakes are high for these two.
'By God, right by the hopur wil I stande,' Quod John, 'and se howgates the corn gas in. Yet saugh I nevere, by my fader kyn, How that the hopur wagges tila nd fra.' (182 – 185)
John and Aleyn's plan to prevent Symkyn from shorting them of their corn is to stand in the room with him as he grinds it. John will watch the corn as it goes into the "hopper" (grinder), while Aleyn stands below it to see the corn as it comes out. In this way, the two hope to prevent the miller from stealing any corn and from padding the sack with a less expensive grain, like bran.
This millere smyled of hir nycetee, And thoghte, 'Al this nys doon but for a wyle. They wene that no man may hem bigyle.' (192 – 194)
Symkyn is immediately on to John and Aleyn's plan to prevent him from stealing their flour. He's totally confident that he'll be able to deceive the two scholars. The miller thinks it's "nycetee" (foolishness) that they think no one can possibly deceive them.
And to the hors he goth hym faire and wel; He strepeth of the brydel right anon. And whan the horse was laus, he gynneth gon Toward the fen, ther wilde mares renne. (208 – 211)
Symkyn releases the students' horse so that they will have to catch it, rather than watch him grind the corn. In this way he hopes to be able to steal from them.
And whan the millere saugh that they were gon, He half a busshel of hir flour hath take, And bad his wyf go knede it in a cake. (238 – 240)
Symkyn steals the clerk's flour and has his wife bake it into a cake. By involving his wife in his trickery, he makes his household an accomplice to theft. Later in the story, his daughter's knowledge of the cake's whereabouts will imply that all of the miller's family is in on his game.
And up he roos, and softely he wente Unto the cradel, and in his hand it hente, And baar it softe unto his beddes feet. (357 – 359)
Here, John plays the "cradle trick" on Symkyn's wife. This trick is a common one in medieval fabliau, or bawdy stories. In it, someone moves a cradle by which a woman knows her bed in the dark. When she finds it at the foot of another bed, she crawls in between the wrong sheets and ends up having sex with a man other than her husband.
Lo, swich it is a millere to be fals! (464)
Here the narrator implies that Symkyn's cheating and deception is simply common to his profession. It makes sense that the Reeve would want to speak badly about the whole profession of millers, because he interpreted "The Miller's Tale" as an insult on the whole profession of carpenters.
And therfore this proverbe is seyd ful sooth, 'Hym thar nat wene wel that yvele dooth.' A gylour shal hymself bigyled be. (465 – 467)
The narrator implies that the "gyle" (deception) of the miller was rewarded with more deception – he was "hymself bigyled." It's true, of course, that Aleyn and John had sex with his wife and daughter secretly, and so, deceptively. But the sting of Symkyn's "punishment" is not that the clerks had sex with his wife and daughter without his knowledge – it's the fact that they had sex with the clerks at all.