This Psalter was written by Carthusian monks. Of all the orders the Carthusian was the smallest and most austere. The membership never exceeded one per cent of those enrolled in the combined monastic orders. The Carthusians were frequently hermits, and manuscripts written by them are rare. The rotunda book hand used in this leaf is representative of the general excellence maintained by Italian scribes at the time when printing was being introduced into their country. The simple melody for the Psalms apparently was added as a somewhat later date. Close observation of the initial letters will frequently reveal a small black letter inserted as a guide for the monk who later added the colored initial. The use of two guide lines for the lettering is unusual. Ordinarily one line, below the writing, was deemed sufficient. The lines were drawn with a stylus composed of two parts lead and one part tin.