Love
In this sonnet, love isn't a mere feeling of affection or even adoration. Instead, it's a force so strong that it's nearly violent. For the speaker, love does, and should, eradicate the identities of the people involved. Therefore, the speaker claims to be indistinguishable from his lover (and vice versa). This indistinguishability is quite literal in some ways: for instance, the speaker describes himself and his lover being physically entwined to such an extent that it's not clear which limbs belong to whom. Love doesn't only dissolve individual identities: it also destroys any other obstacles in its path, rendering conflicts moot before they even begin. In fact, the only conflict that seems to remain in the face of the speaker's love is his struggle to articulate the intensity and power of that love.
Self-expression
At the start of this poem, the speaker ticks off a number of things that his love is dissimilar to, all of them flamboyant and familiar symbols of love: roses, fire, and precious stones. In the end, the speaker concludes, his love is too strongly felt to warrant such a showy and visible comparison. Somewhat paradoxically, it can only be compared to subtler objects, like a plant that is alive but not blooming. Moreover, the speaker says, his love comes from somewhere between "the shadow and the soul," which seems to be a way of saying that it's associated with dark, abstract, and invisible things. Overall, then, the speaker's love is strong but not flashy. It is internal and private, and therefore best expressed through quiet, subtle imagery.
