The author investigates all cases of the order of the infinitive and the atonic pronoun through "La Celestina", one of the Spanish masterpieces of the beginning of the 16th century.
1) In cases that the verbs such as querer, poder or the verb phrases with prepositions go with the infinitive, the pronoun sometimes goes after the verb, which differs from the modern Spanish. It has some relation to a pause of a sentence, but not absolute one.
2) In cases without such verbs above, the pronoun often comes before the infinitive, when accompanied by a preposition. On the other hand, it rarely comes before the infinitive without any preposition.