Dominican Juan de Paz entertained frequent queries on the ethics of usury, which was charging an interest when lending. The topic had been a staple in moral treatises since the classical period. This chapter discusses three inquiries about this ethical quandary. Beyond doctrinal considerations, in the course of his argumentations, Paz describes little-known aspects of the commercial life of Manila and its environs at the time of his writing. Two cases revolve around loans intended for the transpacific trade, one between two Spaniards and another between a Chinese and a Spaniard. As he gives his opinion, Paz expounds on the selling seasons and the changing prices of merchandise. In other segments of the moral interrogations, Paz lets the reader know details of the local and regional commercial transactions of the Indigenous population. What started as moral dilemmas became vignettes of the commercial markets of his time.