Life and planetary orbits are elliptical, circling. Giving requires others receiving - accepting the gift or the help. It seems to promote positive feelings to help others and teaching something can reinforce how well the material is understood.
Older students helping younger students can help both groups to better understand the lesson. For the student teachers, the effect on their remembering the material seems to be based on retrieval memory - knowing the material well enough to simply explain it, rather than reading a prepared script or page of notes. See: Learning by teaching others is extremely effective - a new study tested a key reason why., Research Digest, (digest.bps.org.uk).
Some may feel reluctant to accept help or gifts because they might feel that a favor would then be expected or an equivalent gift owed. The concept of pay it forward, may help bypass that reluctance by encouraging the recipient to view the help or gift as freely given, no expectations of a return exchange of gift or favor, but more of an open-ended idea that maybe at some point in the future the recipient will be in a position to help someone else - paying forward the favor.
Pay It Forward is a book by Catherine Ryan Hyde (1999), that was also made into a movie (2000) with the same name.
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