So the conservative who resists change is as valuable as the radical who proposes it -- perhaps as much more as the roots are more vital than grafts. It is good that new ideas should be heard, for the sake of the few that can be used; but it is also good that new ideas should be compelled to go through the mill of objection, opposition, and contumely; this is the trial heat which innovations must survive before being allowed to enter the human race. It is good that the old should resist the young, and that the young should prod the old; out of this tension, as out of the strife of the sexes and the classes, comes a creative tensile strength, a stimulated development, a secret and basic unity and movement of the whole.
Will Durant
change, conflict, evolution, innovation