John Stuart Mill's On Liberty chapter III, “Of Individuality, as One of the Elements of Well-Being,” paragraph 9 reads:

It is not by wearing down into uniformity all that is individual in themselves, but by cultivating it and calling it forth, within the limits imposed by the rights and interests of others, that human beings become a noble and beautiful object of contemplation; and as the works partake the character of those who do them, by the same process human life also becomes rich, diversified, and animating, furnishing more abundant aliment to high thoughts and elevating feelings, and strengthening the tie which binds every individual to the race, by making the race infinitely better worth belonging to. In proportion to the development of his individuality, each person becomes more valuable to himself, and is therefore capable of being more valuable to others. There is a greater fulness of life about his own existence, and when there is more life in the units there is more in the mass which is composed of them. As much compression as is necessary to prevent the stronger specimens of human nature from encroaching on the rights of others, cannot be dispensed with; but for this there is ample compensation even in the point of view of human development. The means of development which the individual loses by being prevented from gratifying his inclinations to the injury of others, are chiefly obtained at the expense of the development of other people. And even to himself there is a full equivalent in the better development of the social part of his nature, rendered possible by the restraint put upon the selfish part. To be held to rigid rules of justice for the sake of others, develops the feelings and capacities which have the good of others for their object. But to be restrained in things not affecting their good, by their mere displeasure, develops nothing valuable, except such force of character as may unfold itself in resisting the restraint. If acquiesced in, it dulls and blunts the whole nature. To give any fair play to the nature of each, it is essential that different persons should be allowed to lead different lives. In proportion as this latitude has been exercised in any age, has that age been noteworthy to posterity. Even despotism does not produce its worst effects, so long as individuality exists under it; and whatever crushes individuality is despotism, by whatever name it may be called, and whether it professes to be enforcing the will of God or the injunctions of men.

(Above, I modernized the spelling of “developes” to “develops.”)