In section 18.3, Keynes highlights various dynamics at play between economic factors, and how certain series of cause-and-effect can exert a stabilizing force on the economy, rather than a runaway or destabilizing force. For example, he points out how the propensity to consume increases at a diminished rate alongside increases in real income, and thus why increases in investment, which result in increases in real income, do not cause an avalanche of uncurbed increase in consumption to the point of maximum employment.
He ends this section by saying that, even though these stabilizing tendencies can be observed in the economy, it does not necessarily mean that these tendencies constitute the optimal conditions. This implies that there may be a role for the state, qua fiscal and monetary authority, to play in further optimizing these conditions.