Self-preservation

Self-preservation, self-interest or selfishness, caused that any contract could be broken. 

For instance, two people desired the same thing, and that thing they both wanted was available to trade, but the owner of that thing demanded it be sold according to his own valuation.

The owner of that thing, as the trader, was governed by reason devoid of any passion. He merely wanted the equal value he prescribed to the thing, as he calculated it.

But because two people now wanted the same thing, the trader would inflate the cost of that thing, to give it to the highest bidder, the one who was willing to pay for it above its true and real value. 

The trader was then in the superior position, playing these two bidders off against each other to see who would give him the highest price, as determined by their own value they have put onto that thing, which was primarily driven by emotion.

It was especially apparent in the long distance-trade across several countries where there was little or no law or custom of protecting transit trade between China, India and Persia or between Persia and Rome, and the goods in transit was of limited supply.

The overwhelming majority of human beings were selfish in nature, therefore, people were not expected to always behave morally and some individuals were easily tempted due to their selfish nature, at the expense of others, to exploit them.

Selfishness in human nature could not be eliminated or altered by education or self-cultivation,which dismissed the possibility that people could overcome their selfishness and considered the possibility that people can be driven by moral commitment to be exceptionally rare.

Clear and impersonal norms and standards such as laws, regulations, and rules were the basis to maintain order.

As human nature has an unchanging selfish but satiable core, competition for external goods during times of scarcity produces disorder, while times of abundance simply mean that people do not fall back into chaos and conflict but not that they are necessarily nice.

Additionally, people were all motivated by their unchanging selfish core to want whatever advantage they can gain from whomever they can gain such advantage, which especially comes to expression in situations where people can act with impunity.

Everybody was eager to conclude a contract, and bidding for things could get out of hand, when two persons both desired the same thing, but which only one of them could possess, it often resulted in violent fights and the winner, determined by their power, wealth or determination.