How does Shakespeare use images of light and darkness to reinforce an idea about the duality of love in Act 3?Please list a quote or two.

In Romeo and Juliet, Shakespeare uses
chiaroscuro, "an effect of contrasted light and shadow created by
light" as symbolic imagery used to contrast the other dualities in the play: "love and
hate"; "life and death"; and love-sickness and
mating.

"Light" is mentioned 46 times in the play; "day,"
its synonym, is used 88 times:

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Away from the light steals home my heavy
son,
And private in his chamber pens
himself,
Shuts up his windows, locks far daylight
out

Here, Montague
describes Romeo not in terms of darkness (that's not very nice), but in terms of light
(the lack of it) to show his melancholic love-sickness over
Rosalind.

"Dark" and "darkness" are used only 9 times.
 Other words, though, stand for it, namely "night," used 100
times.

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Earth-treading stars that make dark
heaven light:
Such comfort as do lusty young men
feel
When well-apparell'd April on the
heel
Of limping winter treads, even such
delight
Among fresh female buds shall you this
night
Inherit at my
house

Here, Capulet
uses the whole gamut: "dark," "light," and "night" to show how "lusty young men feel"
during April's mating season.

All in all, "light" and
"dark" reinforce the dualities of emotional and physical love.