What song the Sirens sang, or what name Achilles assumed when he hid himself among women, though puzzling questions, are not beyond all conjecture.

Sir Thomas Browne’s line comes from his encyclopedic treatise *Pseudodoxia Epidemica* (also known as *Vulgar Errors*), first published in 1646, in which he examines and corrects widely repeated “common errors” in natural history, medicine, and learning. Writing in the mid–17th century—an era of expanding empirical inquiry but still saturated with inherited authorities—Browne distinguishes between questions that are merely obscure and those that are truly unknowable. By invoking classical curiosities (the Sirens’ song; Achilles’ disguise on Scyros), he frames a broader argument about the limits of certainty while defending the legitimacy of reasoned conjecture where evidence is incomplete.

Browne suggests that some famous mysteries are “puzzling” but not wholly beyond rational investigation. The examples are deliberately tantalizing: they are not matters of practical science, but of lost particulars from myth and legend. His point is methodological: ignorance is not a single category. Between demonstrable knowledge and absolute unknowability lies a middle territory where careful inference, comparison of sources, and probabilistic reasoning can still operate. The sentence thus models Browne’s larger intellectual posture—skeptical of credulity, wary of dogmatism, yet confident that disciplined conjecture can yield meaningful understanding even when definitive proof is unavailable.