How can we interpret Benvolio's lines concerning Romeo in Act 1, Scene 1, lines 122-126 of Shakespeare's Romeo and Juliet ?
I, measuring his affections by my own,
Which then most sought where most might not be found,
Being one too many by my weary self—
Pursu'd my humour, not pursuing his,
And gladly shunn'd who gladly fled from me. (I.i.122-126)
In this passage Benvolio is informing Romeo's parents that the last time he saw Romeo was at dawn this morning. Benvolio, feeling upset about something, went out for an early morning walk, as we see in the earlier line, "A troubled mind drave me to walk abroad" (1.i.116). He then tells Romeo's parents that he saw Romeo by a small wood of sycamore trees on the west side of the city, presumably the part of town where Rosaline lives. When Benvolio starts to head towards Romeo, Benvolio sees him run and hide deeper in the woods. Benvolio then says that he understood it to mean that Romeo wanted to be alone, as we see from the line "measuring his affections by my own," meaning that he used his own emotions to further understand Romeo's (122).
In this passage, Benvolio also tells us that, feeling blue himself, he also wanted to be alone and so he understood Romeo's desire to be alone. We especially see that in Benvolio's next lines, "Which then most sought where most might not be found, / Being one too many by my weary self," meaning that Benvolio's own feelings most desired to be where other people are not present, or alone, and so he easily interpreted Romeo's actions as also saying that Romeo wanted to be alone and that one more person was far too many for either Benvolio or for Romeo.
Next Benvolio says that he decided to continue to coddle his own blue emotions rather than making himself more depressed by finding out what is wrong with Romeo. Instead, since Benvolio did not really want to interact with anyone himself, he kept his distance from Romeo and continued his separate path. We see Benvolio explain this in his last two lines, "Pursu'd my humour, not pursuing his, / And gladly shunn'd who gladly fled from me" (125-126).
In other words, Benvolio is saying in these five lines that feeling blue himself, when he saw Romeo dash into the woods, he interpreted Romeo's feelings as being similar to his own. Benvolio did not want company, nor did he want to make himself feel even more glum by finding out what was wrong with Romeo, so he gladly let Romeo alone and continued on his way.