If you wanted to understand the rise of women in the business world in the second-half of 20th Century, you could do worse than to study the life and career of Mary Kay Ash. A successful salesperson in Dallas, she quit her job in 1963 because, she said, a man whom she had trained was promoted above her at twice the salary. She planned to write a book, but her notes became instead a business plan for a beauty and cosmetics company that relied on women to sell merchandise to their friends and acquaintances through direct sales (otherwise known as multi-level marketing.)

Ash started the business with her son and $5,000 in savings. She was rare among women business owners in that she presided over many stages of growth: she started her company; bootstrapped it during the early years; managed it through rapid growth; and took the business public. Finally, in 1985, she presided over a leveraged buyout that took the business private again. Ash served as chairman until 1987; her son, Richard Rogers, succeeded her as CEO. Today, the business is represented by a network of more than a million independent reps and grosses more than $2 billion a year.

Though Ash's company culture was perceived as something of an oddity by the outside world, her instincts as a leader were in retrospect quite progressive. She was, for example, an early proponent of work-life balance. With the motto "God first, family second, career third," she encouraged sales reps to take control of their work lives -- "They are presidents, literally, of their own little companies, and they can make them as big as they want," she told Inc. -- an enlightened attitude, particularly in the hardscrabble world of MLM.

Ash also helped to popularize the use of lavish incentives as a way to recruit and retain workers and to promote Mary Kay as an employer brand. Beginning in 1969, the company's top reps were rewarded for performance with Cadillacs that were painted pink -- the same color as the entrepreneur's favorite blush. (Ash eventually signed a deal with General Motors to exclusively own the paint color.) Today, nearly 10,000 of the company's top earners drive pink Cadillacs.

Finally, Ash's greatest achievement is that she overturned the notion that women didn't belong in the competitive world of sales. In the 1960s, it was not uncommon for a company's sales force to be made up entirely of men; Mary Kay was the first company with a sales force made up entirely of women, and its financial success opened the door for a generation of women to move into lucrative positions in sales in all kinds of industries.

Ash was aware of this legacy. "I feel like I'm doing something far more important than just selling cosmetics," she told Inc. in 1985. "I think we're building lives."