His second opinion is: contracts say that lawful it is to obtain a thing that costs more than the thing’s price. When a buyer decides he needs some things he looks for a better price that is lower, but not higher. And a seller needs to sell things at a just price. The price of things is their just price. If one person cheats other person, it means they injure these persons. The author thinks that in contracts one way dealing is accepted, not double dealing.
Another point of the author is that buying and selling can be advantage too. An advantage can be when buyer and seller deal on different things. But deal is when people buy or sell things equally. Also one person can get advantage and the other person disadvantage at the same time. Equal they are when things sold and bought have quality and price, and they both are equal.
According to the author, unjust is to buy and sell things with higher and lower prices. He also states that exception can be their just prices. A buyer can pay more if they are satisfied with things they bought. Also the Divine law is saying about justice. Justice is important when buying and selling different things. When justice is present, then buying and selling is always lawful.
Next, the author writes about defects in different things that sellers sell. These sellers may not even know about defects in the things. They cannot avoid them too. The sale then is not unlawful according to law. Often sellers can sell the things that have a low quality. These sellers can do nothing and this is not unlawful too. Sellers do not sin because they do not know of the low quality of his things. But sellers need to pay back money when a buyer finds out about defects and reports them.
In past times gold and silver was handmade because it was rare. Alchemist made gold and silver that was not real and very precious. Gold and silver were of low quality and selling all gold and silver things were unjust. Only if gold and silver was truly real then selling was not unlawful.
According to the author, seller cannot say about defects of their things they are selling. This is because buyers can buy what they like and they are not forced to buy ugly things. The point of the author is if things have defects these things lose real value of the things. But from what Ambrose writes, he says that in contracts all defects must be written about. Also a buyer can sell their different things. Buyers can always name prices they want because they not salesmen. And the author writes this is just thing to do and never unlawful again.