Mahatma Gandhi defined the Law of Progression during his early years in South Africa. According to Gandhi, nonviolence has a magnetic quality that draws more people to it through its implications for action instead of passivity and appeal to people’s basic compassion and respect for life. In his own words,

My experience has taught me that a law of progression applies to every righteous struggle. But in the case of satyagraha [nonviolent action] the law amounts to an axiom. As the Ganga [sacred river in India] advances, other streams flow into it, … So also as a satyagraha struggle progresses onward, many another element helps to swell its current, and there is a constant growth in the results to which it leads. This is really inevitable, and is bound up with the first principles of satyagraha…. The Ganga does not leave its course in search of tributaries. Even so does the satyagrahi [nonviolent leader] not leave his path which is sharp as the sword’s edge. But as the tributaries spontaneously join the Ganga as it advances, so it is with the river that is satyagraha. (Satyagraha in South Africa, p. 173)

The Law of Progression partly explains why large numbers of participants are not essential in Satyagraha: if a satyagrahi remains true to nonviolence principles, numbers and other kinds of strength will flow into the movement as needed.