*Please provide the Act and Scene (and even line numbers) when possible. This makes it easier to find within the play.
"For naught so vile that on the earth doth live
But to the earth some special good doth give;
Nor aught so good but, strained from that fair use,
Revolts from true birth, stumbling on abuse." (II.iii.17-20)
In this scene, Friar Lawrence is commenting on the plants and herbs he is gathering. The friar is in awe of the properties that plants, herbs, and stones have. The friar's knowledge of such natural elements shows that natural elements have both good and bad properties. Even if the plant or herb has poisonous (bad) qualities ("Naught so vile"), it also provides the earth with good, beneficial elements ("But to the earth some special good doth give"). Even though it can be used for good, it's properties are sometims twisted (strained) from being used positively and misused ("Revolts from true truth, stumbling on abuse").
Literary devices: a pair of rhyming couplets (live/give; use/abuse)