Timothy wrote an important treatise on the sacraments of the Church, part of which has been translated into English.

Eznik is also the author of a short collection of moral precepts, printed with his more important treatise.

Ptolemy was the author of two important scientific treatises.

There were then several important treatises concerning or devoted to the viol.

The Zohar, which was written in the 13th century, is generally held as the most important esoteric treatise of the Jews.

Yet this "downtown" composer is also a long-time academic and a respected theorist with a couple of important treatises on music to his name.

In medicine, Hunayn wrote an important treatise on ophthalmology.

His most important mathematical treatise was the Regoluzze, a manual of elementary arithmetic, written in 1340.

In this year, he also wrote an important treatise on the arithmetical triangle.

He wrote an important treatise on riding, Reitlehre (1933), and many works on the history of art.