Prince Alphonso, eldest son of Edward I, was to marry Margaret, daughter of Florent V, Count of Holland, in 1284, but he died before the wedding. This psalter is thought to have been commissioned by Edward I for his son's marriage because of the heraldry painted at the beginning of Psalm 1. The decoration was left unfinished until the early 14th century, when it was filled out in various styles. The first letter of Psalm 38 was decorated in the early 14th century with ornament based on leaf forms and given a touch of fantasy in the human-headed monster writhing amongst the vines. The initial with its heavy application of gold leaf is a luxurious touch, but it also serves a purpose. It marks one of the divisions of the psalter. To organise the cycle of prayer that monks and devout lay people recited on a daily basis, the psalter was divided into eight sections: seven for the prayers said very early in the morning (matins) and one for evening prayers (vespers). The Alphonso Psalter would have been used as a personal prayerbook. Around the time it was made, the first books of hours, special prayerbooks for the laity, were being created based on the ones used by monks.