The subtitle describes the tract as an inventory of remarkable books, antiquities, pictures and rarities of several kinds, scarce or never seen by any man now living.
As the 17th-century Scientific Revolution progressed the popularity and growth of antiquarian collections, those claiming to house highly improbable items grew.
Browne was an avid collector of antiquities and natural specimens, possessing a supposed unicorn's horn, presented to him by Arthur Dee.
The sheer volume of book-titles, pictures and objects listed in Musaeum Clausum is testimony to Browne's fertile imagination.
However, his major editors, Simon Wilkin in the nineteenth century (1834) and Sir Geoffrey Keynes in the twentieth (1924), summarily dismissed it.