Alfonso Martínez de Toledo's Corbacho and Diego de San Pedro's Cárcel de Amor are the Spanish vernacular texts which have contributed the most to Celestina, and it is not surprising to discover that they, as well as the Petrarchan sources, are prominent in the genesis of Pleberio's lament. Rojas undoubtedly took the ‘Llanto de su madre de Leriano’ as the prose model for his lament, although the planctus is a sturdy rhetorical tradition from ancient times and there is no shortage of models. The planctus was an important division of rhetoric with its own rules; it was a digressio from the laus or enkomion, itself a subdivision of the apostrophe. Certain rhetoric and imagery were obligatory: exclamatio and interrogatio, light and darkness imagery, the world-upside-down topic, the exclamation against death. Furthermore, most laments seem to have at least some of the ingredients of grief as it is clinically described in the twentieth century: shock and searching, anger and guilt, bargaining, grief itself, and acceptance.

In Cárcel, Leriano's mother begins with the praise of her son: