Diego de Avendaño, Thesaurus Indicus (Antwerp 1668) vol. 1 p. 325
1. Contract of Slavery is unjust
2. Merchants must examine contracts for justness
3. Merchants who buy a large number of slaves sin mortally
4. Those who buy slaves from those merchants also sin mortally
5. If buyers with good faith later have doubts they do not have to free their slaves
6. Those buyers who purchase slaves in bad faith are held to free their slaves (scilicet ipse Aethiops qui habet ius naturale, et possessionem suae libertatis)