who said to every action there is a reaction
Reaction (physics) As described by the third of Newton's laws of motion of classical mechanics, all forces occur in pairs such that if one object exerts a force on another object, then the second object exerts an equal and opposite reaction force on the first.[1][2] The third law is also more generally stated as: "To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts."[3] The attribution of which of the two forces is the action and which is the reaction is arbitrary. Either of the two can be considered the action, while the other is its associated reaction.
Straw that broke the camel's back The idiom the straw that broke the camel's back, alluding to the proverb "it is the last straw that breaks the camel's back", describes the seemingly minor or routine action which causes an unpredictably large and sudden reaction, because of the cumulative effect of small actions.