John Fletcher's "Upon an Honest Man's Fortune" is a meditation on free will and self-determination, and in the course of praising the self-made honest man it mounts a firm case against astrologers and all who claim that the stars govern human destiny.
Man is his own star. The poem's controlling argument is that a virtuous man is the maker of his own fortune. In the famous lines, "Man is his own star, and the soul that can / Render an honest and a perfect man / Commands all light, all influence, all fate." If the human soul, through honesty, controls light and fate, then the astrologers who read fate in the heavens are usurping a power that in truth belongs to human character. Nothing, the poem insists, falls to such a man "too early or too late."
Our acts are our angels. Fletcher relocates destiny from the sky to conduct: "Our acts our angels are, or good or ill, / Our fatal shadows that walk by us still." The forces that shape a life are one's own deeds, the good or evil that a person does, not the movements of distant planets. This directly denies the astrologer's premise that celestial bodies dictate events.
The charge against astrologers. The case against them therefore has several strands. First, they are frauds who claim to foretell what no star determines. Second, they preach a fatalism that robs men of moral responsibility, teaching people to blame the heavens rather than their own choices. Third, they degrade human dignity by making men the puppets of the stars when in fact the honest soul "commands" fate. The wise and upright man rules the stars; the astrologer would enslave him to them.
Conclusion. The poem's verdict is that astrology is empty and even harmful. By insisting that virtue and action, not planetary influence, decide an honest man's fortune, Fletcher exposes the astrologers as deceivers who deny free will and moral accountability. The case against them is, at bottom, a defence of human freedom and responsibility.