The speaker is trying to untie a knot, but their vision blurs and everything runs together. That blur matches their thoughts, which are just as tangled. The repeated "Yes, very much like my thoughts" sounds like someone admitting something they would rather not.
In the second stanza the poem says outright what the knot stands for: the speaker's mind, trying to open up and failing. The judgment that they "should leave my past behind" sounds like advice they know is sensible but can't follow. The last line changes the tone. "Just like you left me behind" turns the poem toward another person, and it suggests the past they can't let go of is tied to someone who walked away. The speaker is told to leave things behind, yet they were the one left.
The mood is quiet, tired and a little bitter. Nothing dramatic happens, but the stuck, fumbling image makes the hurt feel close and unresolved.