The Problem of the origin of Profit

Hi, I have written a small work on economics. Basically I claim that in an economy with a fixed amount of money, no monetary profit is sustainable. Therefore the government from time to time has to create new money and inject it to circulation.
Here is the article:

The use of the word “profit” is deceptive. When (as Adam Smith first described) a production process takes place, the 3 factor involved are land, labor and capital (or durable capital goods). Their corresponding returns are ground-rent, wages and interest. This last term may be exchangeable with word “profit” since it is the interest that is most likely to vary as the production makes progress. However this word also is applied in other ways, including the other two returns during production. This is very confusing and it should be avoided when possible. The circulation of money is in a closed system (of several circuits) so in theory it will not accumulate and will not need to be replaced.

You can call it however you want… it’s still a fact that people are able to earn more money than they spend… I call it “profit”, you can call it something else… it doesn’t matter.

So what do they do with this extra money? Sooner or later it gets spent and more people owe money than save it. The use of the word profit does not apply here. It is important to think in a logical way about how money circulates.

Not necessarily… maybe it gets spent, and maybe not. You can offer different word, if you don’t like the use of the word “profit”.

I find it really difficult to understand how money accumulates without being spent. A person who saves his/her earnings does not do so for an eternity but sooner or later this money is used for a holiday or a new house purchase or possibly it is bequethed to a family member to be similarly used. When saved money generates interest the total sum in circulation must grow and new money introduced, but since the national deficit is usually increasing, the money that is circulating is eventually spent too. What is the good of having money "under the matress’? --sooner or later it returns to the roundabout of its being in circulation.