Throughout Decameron the mercantile ethic prevails and predominates. The commercial and urban values of quick wit, sophistication, and intelligence are treasured, while the vices of stupidity and dullness are cured, or punished. While these traits and values may seem obvious to the modern reader, they were an emerging feature in Europe with the rise of urban centers and a monetized economic system beyond the traditional rural feudal and monastery systems which placed greater value on piety and loyalty.
Beyond the unity provided by the frame narrative, Decameron provides a unity in philosophical outlook. Throughout runs the common medieval theme of Lady Fortune, and how quickly one can rise and fall through the external influences of the "Wheel of Fortune". Boccaccio had been educated in the tradition of Dante's Divine Comedy, which used various levels of allegory to show the connections between the literal events of the story and the Christian message. However, Decameron uses Dante's model not to educate the reader but to satirize this method of learning. The Roman Catholic Church, priests, and religious belief become the satirical source of comedy throughout. This was part of a wider historical trend in the aftermath of the Black Death which saw widespread discontent with the church.
Many details of the Decameron are infused with a medieval sense of numerological and mystical significance. For example, it is widely believed that the seven young women are meant to represent the Four Cardinal Virtues (Prudence, Justice, Temperance, and Fortitude) and the Three Theological Virtues (Faith, Hope, and Charity). It is further supposed that the three men represent the classical Greek tripartite division of the soul (Reason, Spirit, and Appetite, see Book IV of Republic). Boccaccio himself notes that the names he gives for these ten characters are in fact pseudonyms chosen as "appropriate to the qualities of each". The Italian names of the seven women, in the same (most likely significant) order as given in the text, are: Pampinea, Fiammetta, Filomena, Emilia, Lauretta, Neifile, and Elissa. The men, in order, are: Panfilo, Filostrato, and Dioneo.
Boccaccio focused on the naturalness of sex by combining and interlacing sexual experiences with nature.