Most of us, when we are children, are told that it is polite to say thank you when someone does something nice to you.

The Bible is full of references to thankfulness. In all cases, being thankful is a good thing. And in one case -- Colossians 3:15 -- Paul gives us a direct command that sounds a bit like our mother: "Be thankful," he says.

Several years ago, the Seattle-based Agathos Foundation discovered the power of saying thank you in a real and tangible way.

A Christian magazine had written an article about Agathos work in Africa, and one of the magazine's readers logged online and made a donation.

Marc Fulmer is the chief operating officer for Agathos. "The gift was generous," Fulmer said, "but it was certainly not one of the biggest gifts we had ever received, even then. Still, this was a new donor, from a part of the country where we had not yet received much support, so I called the donor to say thank you."

When Fulmer called, the donor -- actually a married couple -- was not only happy to hear from him, they also said that though they'd been regular givers to other ministries for years, this was the first time anyone had ever picked up the phone to say thank you.

During that phone call, they wanted to know more about the ministry.

"It quickly became clear that this first donation was just their way of encouraging us and engaging us. They wanted to find out more about our work," Fulmer said. "So we talked about our orphanage, and our other work, and they had intelligent questions. They would ask why we weren't doing certain things. Sometimes my answer was that those things were not a part of our focus, or not what we thought we were best at. Other times, I said we wanted to do those things but currently lacked the resources."

Those honest answers must have given these donors confidence both in Fulmer and in Agathos.

By the end of the conversation, they had asked Fulmer to prepare an itemized list of the current needs of the ministry. "I put together a list of things we had talked about, and many more that we hadn't talked about," Fulmer said, "everything from a new set of tires for a truck we had in Africa to tools to build new structures in the village."

Fulmer said none of the items was terribly expensive, but he also said that he filled up a typewritten page of needs, each one with a cost, and a total at the bottom: nearly $70,000.

Fulmer told Agathos Foundation founder and president Rob Smith about the conversation and said he anticipated this donor would look at the list, pick out an item or two, and send a check to cover those items. But a couple of weeks later, a letter arrived.

"Back in those days, we were still mostly working out of our home," Fulmer said. "It was my habit to pick up the mail from a post office box and go over to Rob's house and go through the mail together. But I couldn't resist opening this letter, and when I saw it, I couldn't believe my eyes.

Rob Smith takes up the story: "Marc put the letter at the bottom of the stack, so by the time I got to it I had waded through junk mail and bills. Stuff that was either a waste of time or a problem to be solved. It was pretty discouraging until I got to the bottom of the stack. It was a check for the full amount. They had paid for everything on the list. This was by far the biggest gift we had ever received."

Later, this couple did the same thing again. "We've so far received more than $140,000 in donations from them," Fulmer said.

Did all this happen because of a simple thank you? "This donor embraced our vision quickly," Rob Smith said. "I think what they really wanted to know was whether we could deliver on the vision. When Marc called her to say thank you, I think he showed both a servant's heart and an attention to detail that gave them confidence to do more with us."

Smith is also quick to point out that the words "thank you" should not be treated as the password of an automated teller machine. "We say thank you because we are genuinely grateful," he said, "not because we expect something in return. Even so, gratitude is sometimes the seed that results in even greater generosity -- and greater opportunities for gratitude -- in the fullness of time."

Warren Cole Smith is the publisher of the Evangelical Press News Service.