Earlier this year Historical & Special Collections acquired a 1571 edition of the Spanish bishop and jurist Diego de Covarrubias y Leyva’s Clementinae, si furiosus, de homicidio, relectio—a treatise on murder published in Salamanca.

While cataloging it, I couldn’t help but notice a half-size sheet of paper tipped in following the title page.
The wording looked vaguely familiar, one of the preliminaries that readers usually skips over to get to the main text. But the fact that this slip of paper appeared to be a last minute addition caught my eye. What exactly was it anyway? And how was it related to the phrase at the foot of the title page: “Esta tassado en“?

The slip of paper turns out to be a tasa (or tassa) the maximum retail price allowed for the book. This was established by the powerful Council of Castile and certified by an “escrivanos” (a clerk or notary)–in this case one Domingo de Zavala. The price of books had been regulated by law since the late fifteenth century. This price cap was based on the number and size of sheets of paper used in the production of every book published in Castile, no matter what the topic.
In the case of this slender volume of canon law, the maximum price was three maravedis per sheet. The sheets referred to in this book’s tasa (“cada pliego escripto de molde”) are the printed sheets as they came off the press— not the actual pages in the final product. This is because in the hand-press period (approximately 1455 to 1830) a single sheet, folded and cut, could produce anywhere from two to sixty-four pages, depending on the desired size of the finished book.
Unlike the tasa inserted into this copy of Covarrubias’ work, most tasas, sometimes combined with licenses, are clearly identified as such:

Sometimes the tasa is stated simply at the foot of the title page:

Perhaps the latter option was the original intention in Covarrubias’ 1571 edition …
… but for reasons unknown the maximum retail price established for the book was never added so the separate tasa statement needed to be inserted after printing.
In addition to capping book prices, the Council of Castile had a firm hand on the business of publishing and printing books in other ways. This included the issuing of licenses to publish, privileges (the right to reprint), censorship, and other forms of governmental oversight. The Spanish book trade continued to be tightly regulated well into the eighteenth century, but the tasa for books was discontinued in 1763, early in the reign of Carlos III, King of Spain.