In "The Collar," the speaker is complaining about the constraints of living a moral and virtuous life. In the first two lines, he decides he has had enough, striking a board and crying "No more, I will abroad!" He decides to leave this way of life. He feels freed by this rebellion. He then thinks about his moral life being one of servitude; the only fruits of his "harvest" are the thorns of the plant. (This may also be a reference to Christ's crown of thorns, one of the burdens of his sacrifice.) During his religious life, he recalls not partaking of the wine (his "sighs did dry it").
He resolves to make up for lost time, to "recover all thy sigh-blown age / On double pleasures:" (19-20). He resolves to indulge in those things which he, under his moral restraint (his "collar," hence the title), would not allow himself to enjoy. He wants to be released from this collar, this "cage" or "rope of sands." The speaker thinks that anyone who denies himself pleasure deserves the burden of a strictly moral life:
He that forbears
To suit and serve his need,
Deserves his load." (30-32).
The quotation mark at the end of this statement marks the end of his complaint. As he finishes up with his rebellion against living a strict, moral life, he hears the voice of God and he is at peace once more. The implication is that even the most righteous ones have doubts and despair. This rant the speaker proclaims is cathartic and the speaker is reminded of God's patience and forgiveness, which is why at the poem's end, he sees his "collar" is not a restraint but a patient guide.
Given that the poem is written from the point of view of a Protestant minister, explain the significance or connotation of the word “fruit” in line 17 in George Herbert "The Collar"