The Friar knows human character as well as plants
Friar Lawrence ends up playing a key part in the tragic love story of Romeo of Juliet, despite being a relatively minor character. Although Catholics were not generally looked upon with a friendly eye in the Elizabethan era, Shakespeare generally describes the Friar in a respectful way.
He appears to be a kind, sensible man who is a good judge of human character. For instance, he explains to Romeo that his feelings for Rosaline were not real love and that she knew it: “O, she knew well/ Thy love did read by rote that could not spell.” (2.3.88-89)
When we first meet Friar Lawrence it is in Act 2, Scene 3 where he is gathering herbs. He delivers a soliloquy on the healing or fatal power of plants:
For nought 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.