Diversity of language serves two important ends of the human spirit, a use of unification and a use of variation. A language helps to bring those who speak it into a certain large unity of growing thought, formed temperament, ripening spirit. It is an intellectual, aesthetic and expressive bond which tempers division where division exists and strengthens unity where unity has been achieved.
Especially it gives self-consciousness to national or racial unity and creates the bond of a common self-expression and a common record of achievement. On the other hand, it is a means of national differentiation and perhaps the most powerful of all, not a barren principle of division merely, but a fruitful and helpful differentiation.
For each language is the sign and power of the soul of the people which naturally speaks it. Each develops therefore its own peculiar spirit, thought-temperament, way of dealing with life and knowledge and experience. If it receives and welcomes the thought, the life-experience, the spiritual impact of other nations, still it transforms them into something new of its own and by that power of transmutation it enriches the life of humanity with its fruitful borrowings and does not merely repeat what had been gained elsewhere.
Therefore it is of the utmost value to a nation, a human group-soul, to preserve its language and to make of it a strong and living cultural instrument. A nation, race or people which loses its language cannot live its whole life or its real life. And this advantage to the national life is at the same time an advantage to the general life of the human race. Language is the sign of the cultural life of a people, the index of its soul in thought and mind that stands behind and enriches its soul in action. Therefore it is here that the phenomena and utilities of diversity may be most readily seized, more than in mere outward things; but these truths are important because they apply equally to the thing which it expresses and symbolises and serves as an instrument.
Diversity of language is worth keeping because diversity of cultures and differentiation of soul-groups are worth keeping and because without that diversity life cannot have full play; for in its absence there is a danger, almost an inevitability of decline and stagnation.