In act 1, scene 5, immediately after Romeo and Juliet have first caught one another’s eye, Romeo compares their hands to lips. He has already compared Juliet to a “holy shrine” and described his own hand as being unworthy to touch her (1.5.105). Further, he compares his own lips to “two blushing pilgrims” who would long to press themselves against her, as one might kiss a holy shrine (1.5.106). Juliet suggests that placing their hands “palm to palm” is one way for pilgrims to touch the hands of shrines and statues of saints, and that this is the way that they can kiss, so to speak (1.5.111). She also claims that pilgrims should use their lips for prayer rather than for something else, like kissing. However, Romeo says that “lips [should] do what hands do” and pray, pressing against one another so that faith does not turn to despair (1.5.114).
Thus, Romeo compares Juliet to a holy shrine, as one dedicated to a saint, and he compares their hands to lips, hoping to kiss her (which he does do, a couple of times!). Juliet plays into the metaphor by entertaining and helping to develop it. This type of language, language of holiness and divine objects, seems to suggest that Romeo and Juliet’s relationship will develop quickly, as both discuss a kind of devotion and faith not necessarily consistent with young love or love at first sight.