If someone relies on slaves to do their work that person will not care how efficient or how hard it is to do that work. For example, the Greeks did not believe in work and had lots of slaves. When the Greek empire started to fall, they started to lose all of their slaves, and then they were almost helpless because they normally had slaves to do their work. They started to realize that it would be better if they had inventions. Then, all that work would go faster and they would have more time to play.
The Monks did not have any slaves and had to do all the work themselves. They were more creative so they were constantly inventing more things to help them get more work done. They worked more because they thought they were here to work and serve others.
Capital is any asset one uses to produce goods or services. For example, tools and ethics are common ones. The monks had more capital than the Greeks because they had a stronger work ethic and invented more things.
So as one can see, if one does the work himself that person might invent an invention to help their job go faster. Which will increase their capital because working helps increase capital.