Ff. 145r-190v contains the first five books of Galen's De simplici medicina, part of a longer treatise on simply medicines, or the medicinal properties and uses for plants, animals and minerals. The first five books, contained here, specifically deal with the correct way to use such drugs. Galen's work here goes beyond that of others, who simply describe the'simples'. The Latin translation contained in MS 166 of De simplici medicina is by the 12th-century translator, Gerard of Cremona.

The text begins with Book I, on f. 145r with Non est mihi necesse hic ostendere... Book II is contained on ff. 154v-164v, Book III on ff. 164v-173v, Book IV on ff. 173v-182r, and finally Book V is on ff. 182r-190v. The treatise ends (with Book V) on f. 190v: per se si deus voluerit. Finitus est tractatus quintus libri galieni in medicinis singularibus.

In the hand of the second scribe contained in MS 166.