In the "Peanuts" comic strip drawn by Charles Schulz, the scene is a classroom on the first day of school. The students have been asked to write an essay about their feelings on returning to school.

In her essay, Lucy wrote: "Vacations are nice, but it's good to get back to school. There is nothing more satisfying or challenging than education, and I look forward to a year of expanding knowledge."

The teacher compliments Lucy on her fine essay.

Leaning over to Charlie Brown, Lucy whispers, "After a while, you learn what sells."

Sales is the lifeblood that drives business. As I always say, there are no jobs unless someone brings the business through the front door. Career success often depends on your ability to sell a product, a service or an idea. No matter what field you're in, you'll sell better by remembering these key pieces of sales wisdom:

-- Satisfy the customer. There's a meat counter in the supermarket in my neighborhood. There are always three or four clerks waiting on customers. But one of the clerks always has customers waiting for him even if one of the other clerks isn't busy.

One day I asked him the reason for his popularity. He said: "The other clerks always put more meat on the scale and then take some away to arrive at what the customer ordered. I always put less on the scale and then add to it. It makes all the difference."

-- Show, don't just tell. A salesperson tells, a good salesperson explains and a great salesperson demonstrates. A company was selling unbreakable mirror glass and had a sales contest. At the awards banquet, they asked the no. 1 sales rep what his secret was. He explained that he had the factory cut him several 4-by-4 squares of the mirror glass. When he went out on calls, he would put one of the squares on the customer's desk and then take out a hammer and try to smash it. It wouldn't break -- and the impressed customer was sold.

-- Sell what's on the truck. Years ago in New York City, an Italian fruit vendor was teaching his son the basics of salesmanship.

"Don't tell people we are out of peaches," the father said patiently. "Ask them to buy some of our very fresh plums. Sell what's on the truck."

Many of today's salespeople could take the same advice. Don't spend a lot of time complaining about the current state of the product line, or describing products you can't deliver right away. Sell what's on the truck, and your customers will be well served with the quality products you can deliver to them right now.

-- Get in front of prospects. Every sale starts with a prospect -- a potential customer with an interest in what you've got to sell. Identify those who need what you're offering. Find out where they are so you can target your sales efforts effectively.

-- Profile your buyers. Your product should fill a defined need. Analyze the kind of people who might benefit from what you've got to offer so you can tailor your pitch to them. Do they already use something similar? Do they need to be educated about what you can do for them?

-- Get into the customer's mind. You have to tailor your approach to match individual buyers. Once you've targeted specific prospects, spend some time getting to know their personal priorities and professional preferences, and what they're looking for when they consider products like yours. You'll do a better job of selling to them if you focus on satisfying their requirements instead of your own.

-- Know when and how to ask for the sale. Author Murray Raphel offers these words of wisdom: "A 'closing' ... defeats your primary goal in selling: the lifetime value of the customer. You don't 'close' the sale. You 'open' relationships. Isn't the end of the first sale really the beginning of the next sale to the same customer?"

-- Ask for the order. I can't believe how many salespeople do everything right, but then they fail to ask for the order. Often that's the most important part of the process.

An insurance agent, a longtime friend of Henry Ford's, once asked automobile pioneer why he never got any of Ford's business.

"You never asked me," Ford replied.

Mackay's Moral: The hardest part of the sale is selling yourself to your customer.

October 1993 was the beginning of one of my favorite ventures: my weekly column. Twenty years of sharing stories and advice have passed quickly and have taught me many lessons about the nature of business.

Did I have a long-term plan in mind when I started writing? Only to provide the most helpful information available. As I research topics, I learn plenty myself. I've offered both successful and embarrassing stories from my personal experiences. I have drawn inspiration from readers who challenge me, and I am always delighted to hear that a particular column had a positive impact on a reader's career or life. Newspapers all around the country carry my column every week, plus 50,000 people subscribe to it for free on my website, www.harveymackay.com.

My favorite part of each column, as often echoed by readers, is Mackay's Moral, which sums it up in a memorable lesson.

I'm celebrating this milestone by highlighting 20 of the most important morals that have run with these 1,000-plus columns:

-- People become successful the minute they decide to be. A goal is a dream with a deadline.

-- People don't plan to fail; they fail to plan. It's easier to prepare and prevent than to repair and repent.

-- Practice makes perfect ... not true. You have to add one word: Perfect practice makes perfect. Amateurs practice until they get it right. Professionals practice until they can't get it wrong.

-- They don't pay off on effort ... they pay off on results. A lot of people work very hard but never seem to make any headway. Always keep an eye on the finish line.

-- Knowledge does not become power until it is used. There are plenty of people who know it all but have never bothered to do any of it. Ideas without action are worthless.

-- I know that you don't know ... but you don't know that you don't know. Ignorance is not the problem -- it's not knowing we are ignorant that causes difficulty.

-- Your day usually goes the way the corners of your mouth turn. The most powerful single thing you can do to influence others is to smile at them.

-- Time is free, but it's priceless. You can't own it, but you can use it. You can't keep it, but you can spend it. Once you've lost it, you can never get it back.

-- The single biggest tool in any negotiation is the ability to get up and walk away from the table without a deal. Smile and say "no" until your tongue bleeds.

-- You don't have to know everything as long as you know people who do. If I had to name the single characteristic shared by all the truly successful people I've met over my lifetime, I'd say it is the ability to create and nurture a network of contacts.

-- It's never right to do what's wrong, and it's never wrong to do what's right. You cannot do business without trust.

-- Some people go around all of their life asking, "What should I buy? What should I sell?" Those are the wrong questions. Timing is everything. Start asking, "When should I buy? When should I sell?"

-- When a person with money meets a person with experience, here is what happens: The person with the experience winds up with the money and the person with the money winds up with the experience.

-- You will never get ahead of anyone as long as you are trying to get even with them. Helping someone up won't pull you down.

-- The biggest room in the world is the room for improvement. If you think education is expensive, try ignorance.

-- The best place to find a helping hand is at the end of your arm.

-- There will always be a place in the world for anyone who says, "I'll take care of it," and then does it. Remember the 10 most powerful two-letter words in the English language: If it is to be, it is up to me.

-- Failure is no more fatal than success is permanent. You don't quit trying when you lose; you lose when you quit trying.

-- People don't care how much you know about them once they realize how much you care about them. Caring is contagious -- help spread it around!

-- We are judged by what we finish, not by what we start. And this seems like the perfect place to finish.

Mackay's Bonus Moral: Gratitude should be a continuous attitude. Thank you, readers!

I've always been a city boy -- I can't even coax a weed to grow. But I discovered a national treasure, practically in my own backyard, which made me wish my thumbs were greener.

Donna Frantz's greatest skill is not really the organic farming that has dominated her life for the last 16 years. No, she is the poster child for living your dreams with energy and passion. At age 81, she is not about to stop learning and doing new things.

You read that right -- age 81. Donna and her husband, Leon, started a seasonal farmers market that eventually grew into a year-round florist and gift shop that they operated for 21 years. She really wanted a farm, though, and looked for one for 19 years. A farmer finally asked her if she was still interested in buying, and told her he would sell the next year. "I've already waited 19 years," she told him. "I can wait for one more."

So at age 65, when most folks are seriously contemplating retirement, they moved to the farm -- her "25 acres of gold." I recently spent four hours there as Donna proudly showed me her farm. I even had a chance to ride on her tractor, a first for me. As long as she can physically work the farm and her mind stays sharp, there is no desire to retire.

"The soil around Waconia, Minn., is rich and black and perfect for my lifelong dream to grow and share these fabulous vegetables with people," Donna says. She is an organic gardener, and has been all her life. The produce is picked fresh daily, washed and brought into the lower level of their renovated and restored 1890s German bank barn, which houses her business, At the Farm. The stone walls keep the space cool, even on the hottest days of summer.

Besides produce, she also sells seeds, herbs, flowers and vegetable plants. Her five employees, whom she refers to as her "elves," taste everything before they sell the crop -- just to be sure it meets her standards.

But the most important commodity Donna dispenses is wisdom: farming advice to be sure, but also motivation, dedication, common sense, and how to live with passion.

Her mom and dad were farmers. Her mother told her never to be a farmer. "Mother had an A-plus work ethic," Donna said. "Dad was outgoing with a terrific sense of humor. Dad said never, never, never worry. He just flew by the seat of his pants and had a let-it-flow attitude."

To live her dream, she ignored her mother's advice. She works every day -- seven days a week. She's never had a vacation. Her vacation is on the farm. She doesn't go anywhere else. She loves work and can't believe she created this.

Every morning, she gets on her tractor and travels around her farm and continually reminds herself that all this is beyond her wildest dreams. She reads self-help books, not for enjoyment, but to learn. She says you cannot learn enough in a lifetime.

I asked one of her employees to share Donna's secret: "She's always in the moment. She always wants to know what is going on in our lives and the lives of customers -- success of kids, sickness, vacations, everything." We do something similar here at MackayMitchell Envelope with our Mackay 66 customer profile.

Then I asked Donna to prioritize what made her successful. Aside from her first answer, which is what every good farmer would tell you, the rest of her advice is universal, regardless of the business you're in.

1. Soil. The soil smells good after it rains.

2. Quality of products. It's important to not be too economical and don't let the cost of your seed get in the way of quality. You must have good seed to be successful.

3. Research, research, research. If it's a new seed, you test and test. You will never know how good it is until you grow it and try it.

4. Be good to your customers. Tell them when you don't know.

5. Above all, you must be honest.

6. Stand behind your product. If someone gets a bad melon, they can throw it away and get a new one.

Donna said, "I don't care how many zeros you have in sales -- from $1 million to $100 million -- business concepts won't change. It's better than money when people like what you do."

Mackay's Moral: It's never too late to plant the seeds of success.