The 5 basic truths are:
When you work for an employer, you have only one customer. When you lose that customer, you lose perhaps your only stream of income.
When you work for an employer, you are working to build or maintain his business.
When you are in employment, you are exchanging your time for money. Sometimes you land up giving more time that you are paid for.
You are really your longest employer. You are your greatest asset. That is why you should always pay yourself first.
Between you and his business, the business owner care only about his business. Between you and his job, your boss care only about his job.