As he gathers herbs in the early morning, the priest, who spends much of his life in solitude, finds mythic beauty in Nature as the sun rises, "Titan's fiery wheels" (2.3.4). Then, as he turns his attention to his gathering of "baleful weeds" that in the right measure can produce beneficial effects, he observes the paradox of nature that benefits can come from those things that are harmful,
For naught so vile that on the earth doth live
But to the earth some special good doth give (2.3.17-18)
However, by the same turn, that which is good, if abused, can then become harmful,
Nor aught so good but, strain'd from that fair use,
Revolts from true birth, stumbling on abuse.(2.3. 19-20)
Thus, the friar summarizes,
Virtue itself turns vice, being misapplied,
And vice sometime's by action dignified (2.3.21-22)
These observations of Friar Laurence are but reiterations of the theme of the antithesis of love and hate in Shakespeare's Romeo and Juliet. For, these emotions, too, can easily transform into the other, just as the herbs that Friar Laurence gathers can alter themselves from salubrious to deadly. In fact, the priest observes at the end of his soliloquy that man, like the plants, can be altered from good to bad if the negative traits in him are more than that which is positive,
In man as well as herbs—grace and rude will;
And where the worser is predominant,
Full soon the canker death eats up that plant (2.3.27-30)
Then, when Romeo rushes into his cell, Friar Laurence is amazed at the change in the young man who has been in love with Rosaline, but now declares his passion for Juliet. He cautions Romeo,
Wisely, and slow. They stumble that run fast (2.3.97).
Clearly, too, there is another theme present here--that of moderation as the key to existence, whether one consume plants or is in love.