Now, the speaker shifts gears. Instead of talking about Love and what Love did to his eyes, now he is talking about his eyes specifically.
Here, he says that his eyes are "corrupt." (Once again, the grammar of this phrase might be a little tricky. You just have to imagine that there is some word like "made" that is there, but invisible—so that the line really says, "If eyes, [made] corrupt by over-partial looks.")
But what "corrupted" his eyes? He tells us: "over-partial looks." What does that mean? Well, it actually could mean a few things.
Going with the primary meaning of "partial" as the opposite of "impartial," or detached, we can think of "over-partial" as meaning super-attached, in love. So, we get two interpretations of the line: either the speaker’s eyes are corrupted by the "over-partial looks" (the loving looks) his lady-love sends him, or they are corrupt themselves because of the "over-partial looks" (again, looks of love) they lavish on her. Actually, it seems pretty easy to imagine both things going on at the same time, doesn’t it? We sure think so. So, this line is talking about how the (apparent) emotional attachment between the speaker and the lady has made his eyes "corrupt."
But wait a second. There might be a secondary meaning of the word "partial" that DOES come from meaning "part of" something bigger. (Although, the important thing to remember here is that, in a poem, the fact that a word has secondary—or third-level, fourth-level, or whatever—meanings doesn’t make the primary meanings untrue. What’s special about poems is that you get to have many, many levels of meaning going on in a single word at once.)
One more thing: We apologize in advance, because the discussion here is about to get mildly X-rated.
Figured it out yet? That’s right: "partial" could mean "having to do with certain parts of the anatomy." Thus, "over-partial looks" would be looks that have "too much to do with certain parts of the anatomy."
Just as with the primary meanings of "partial," however, we’re still left with two choices about how to interpret this turn of phrase: whose "part" does it refer to—the lady’s or the speaker’s?
If it refers to the lady’s, then it means that the speaker’s eyes have been made "corrupt" by staring too long at a certain "part" of her anatomy. We think this is a perfectly likely explanation.
But there’s still one more possibility:
The other way of reading the secondary meaning of this line—the one we’re leaning to—is that the speaker’s eyes are made "corrupt" by "looks" that are "over[ly]" influenced by his own "part." That is to say, his eyes aren’t working right, because he, the speaker is Shakespeare’s sonnet, is being guided by his sexual urges.
Phew. That was complicated. And a little obscene. But we still really have no idea where this sentence is going—we still don’t know what that "If" is doing there at the beginning of the line. Let’s move on to Line 6.
Be anchored in the bay where all men ride,
Alright, we hope you brought your inappropriate imagination with you, because you’re definitely going to need it to decode this line.
Remember that the speaker is talking about his "eyes." These eyes, he has just told us (in line 5) are made "corrupt" by "over-partial looks"—with all the many meanings of "over-partial" that we just talked about.
Now, he tells us what those eyes are looking at. Don’t worry if you didn’t catch this at first. That’s because the speaker says this through a metaphor, and metaphors are often a little bit tricky to make sense of.
The metaphor in this case centers on the word "anchored." Have you ever heard someone say that they "can’t take their eyes off" something or someone else? That’s the idea here. The speaker is saying that, when he can’t take his eyes off something, it’s like his eyes are anchored to that thing.
So, what is that thing? Well, it seems pretty clear the "the bay" in question is a reference to the lady’s, well… most intimate of areas. And we’re guessing that the fact that "all men ride" there means that the speaker’s lady friend gets around with… everybody.
But we’re still missing some information, aren’t we? Shakespeare’s speaker has asked "If my eyes, which have been made corrupt by over-partial looks (Line 5) are anchored in the bay where all men ride"… well, what then? We don’t know! Let’s move on to Line 7.
Why of eyes' falsehood hast thou forgèd hooks,
Aha! Now, the speaker makes clear what he’s talking about. What he’s really doing is complaining about how Love keeps piling on more and more troubles.
We know that we haven’t heard about Love for a while, but the speaker is still talking in an apostrophe to the same "blind fool" from line 1.
Now he says, to Love, "Why do you have to go and make my life that much more difficult by taking my eyes' falsehood and forging it into hooks"?
Note that, when the speaker says "forged" he doesn’t mean in the sense of "forgery," (i.e., fakery). He means in the sense that a blacksmith "forges" something out of metal. Basically, the word here just means "made."
So far so good—but notice that this line ends with a comma; the speaker isn’t even finished complaining yet! Alright, maybe we’d better hear the poor sap out. On to line 8 we go.
But! Before we do, did you notice anything odd about this line? Maybe, we don't know, an odd accent mark or something? That's right! "Forgèd" has an accent mark to indicate which syllabus in that word should be stressed. Typically, we you say the word "forged," you pronounce it as one syllable. Here, though, that accent mark tells us to say "forge-ED," to really break the word up into two syllables. Why would Shakespeare do such a thing? It helps to maintain the line's iambic pentameter. What's that about? Read all about it, gang, in the "Form and Meter" section.
For now, though, it's on to line 8…
Whereto the judgment of my heart is tied?
Let’s start off with the first word of this line: "Whereto." This is just an old-fashioned way to saying "to which." So, what does this refer to? The "hooks" at the end of line 7.
So, the speaker is saying that not only has Love forged his "eyes' falsehood" into "hooks," but also that the "judgment of my heart" is "tied" to those hooks.
What does that mean?
Well, first-off, we've got more personification on our hands here. It's common to think that that heart can act, or have judgment, in human ways, but really, it's just a muscle, gang. And, in a two-for-one special, we also have synecdoche, or using a part (the heart) to represent the whole (really, the speaker is talking his own judgment as a person here).
Secondly, think back to that anchor metaphor from the previous line. As you probably know, an anchor is a special kind of weight used to hold a ship in place. Well, we’ve heard about the "anchor," and we’ve heard about the "hooks" of the anchor, but aren’t we still missing something? Why yes—the ship, of course! Now, the speaker reveals what the "ship" is: the "judgment of my heart."
Still, couldn’t we break this down into simpler terms? Let’s give it a go:
Basically, the whole gist of the poem's second quatrain up to this point is that the speaker thinks Love has totally messed up his life. It was bad enough that he couldn’t take his eyes off this promiscuous lady, but then Love had to go and make him have feelings (this is what he means by the "judgment of [his] heart") for her too.