While Seisetsu was the master of Engaku in Kamakura he required larger quarters, since those in which he was teaching were overcrowded. Umezu Seibei, a merchant of Edo, decided to donate five hundred pieces of gold called ryo toward the construction of a more commodious school. This money he brought to the teacher.
Seisetsu said: "All right. I will take it."
Umezu gave Seisetsu the sack of gold, but he was dissatisfied with the attitude of the teacher. One might live a whole year on three ryo, and the merchant had not even been thanked for five hundred.
"In that sack are five hundred ryo," hinted Umezu.
"You told me that before," replied Seisetsu.
"Even if I am a wealthy merchant, five hundred ryo is a lot of money," said Umezu.
"Do you want me to thank you for it?" asked Seisetsu.
"You ought to," replied Uzemu.
Why should I?" inquired Seisetsu. "The giver should be thankful."
Anthropologically, we do not trade things (including money) unless what we are trading for has more value to us than what we're trading. An excellent example of this is: Food.
You don't get out of bed at 9 A.M., drive 5 blocks to the supermarket, and trade $50 for $50 worth of food. If you did, you'd have put in WAY more to get the food than the food was actually worth.
No, your food is worth more than the gas, the time it took you to get out of bed, and the $50 you put into it. Things rarely sell at their true value; Otherwise, pawnshops wouldn't exist. If you are the giver of money, then anything you give to, is inherently worth more to you than what you are giving.
In Christianity, many churches have a concept of The Denial of Someone's Blessing. The same concept is why western societies tip their servers. You see, if God places it on someone's heart to bless you, the blessing is two-fold. What is on one side of the scale, is equally present on the other. Denying someone the ability to bless you also denies them the ability to bless themselves.
It is on this note that both the giver and receiver should be thankful: the giver for being received and the receiver for being given.