In 1925 Kano Jigoro explained why it is necessary to advocate the principles of mutual prosperity and help in human society 1925.

As long as we coexist, each member of society and the groups organised within must function in harmony and cooperation with the others. Nothing is more important than living prosperously together. If everyone acts with the spirit of mutual cooperation, each person’s work benefits not only himself, but also others, and attaining this together will bring mutual happiness. Activities should not engaged in simply for self-interest. Once started, it is only a matter of course that a person will find goodness in harmony and cooperation upon realising that his efforts will increase the prosperity of all. This great principle of harmony and cooperation is, in other words, the concept of Jita-Kyoei, or mutual prosperity for self and others. Where should one seek the rationale for acting for the sake of others?

Further, if one acts out of concern for his own wellbeing, there will inevitably be a collision of interests with others. Acts for the sake of self-interest will ultimately become a great inconvenience. In this way, sacrificing oneself without any purpose or reasoning runs counter to the greater good of humanity. If one merely enforces his own selfish claims, not only will he become hindered by opposition from others, but such selfishness will lead to self-destruction.

When considered in this light, there is no other way forward but Jita-Kyoei in which all people play their part in society to prosper mutually.
For example, if three people join together in travel, one person may wish to go to the mountains, one to the sea, and one may want to stop and rest. The three eventually come to a point where they all wish to separate. Assuming that they wanted to enjoy the benefits of travelling together at the start, they must cooperate and accede to each other’s wishes. In truth, there is no choice other than to select a common destination to satisfy everyone.