Theorem painting was a popular pastime for young women from about 1800 to 1840. The painting was done using stencils, either ready-made, or hand-drawn and cut out. Early theorem painting was on velvet, but linen, silk, cotton, paper and board were also used. Most are not signed or dated. American theorems made before 1840 are prized by folk art collectors.

Pictured is a contemporary version of a 19th century theorem by a Pennsylvania artist that sold at a Conestoga auction in Pennsylvania. It is 14 1/2 by 17 1/2 inches and sold for $81.

Find more prices of theorems here and in Kovels' Antiques & Collectibles Price Guide 2011.