Herder gave Germans new pride in their origins, modifying that dominance of regard allotted to Greek art (Greek revival) extolled among others by Johann Joachim Winckelmann and Gotthold Ephraim Lessing. He remarked that he would have wished to be born in the Middle Ages and mused whether "the times of the Swabian emperors" did not "deserve to be set forth in their true light in accordance with the German mode of thought?". Herder equated the German with the Gothic and favoured Dürer and everything Gothic. As with the sphere of art, equally he proclaimed a national message within the sphere of language. He topped the line of German authors emanating from Martin Opitz, who had written his Aristarchus, sive de contemptu linguae Teutonicae in Latin in 1617, urging Germans to glory in their hitherto despised language. Herder's extensive collections of folk-poetry began a great craze in Germany for that neglected topic.

Along with Wilhelm von Humboldt, Herder was one of the first to argue that language determines thought, a theme that two centuries later would be central to the Sapir-Whorf hypothesis. Herder's focus upon language and cultural traditions as the ties that create a "nation" extended to include folklore, dance, music and art, and inspired Jacob and Wilhelm Grimm in their collection of German folk tales.

Herder attached exceptional importance to the concept of nationality and of patriotism – "he that has lost his patriotic spirit has lost himself and the whole worlds about himself", whilst teaching that "in a certain sense every human perfection is national". Herder carried folk theory to an extreme by maintaining that "there is only one class in the state, the Volk, (not the rabble), and the king belongs to this class as well as the peasant". Explanation that the Volk was not the rabble was a novel conception in this era, and with Herder can be seen the emergence of "the people" as the basis for the emergence of a classless but hierarchical national body.

The nation, however, was individual and separate, distinguished, to Herder, by climate, education, foreign intercourse, tradition and heredity. Providence he praised for having "wonderfully separated nationalities not only by woods and mountains, seas and deserts, rivers and climates, but more particularly by languages, inclinations and characters". Herder praised the tribal outlook writing that "the savage who loves himself, his wife and child with quiet joy and glows with limited activity of his tribe as for his own life is in my opinion a more real being than that cultivated shadow who is enraptured with the shadow of the whole species", isolated since "each nationality contains its centre of happiness within itself, as a bullet the centre of gravity". With no need for comparison since "every nation bears in itself the standard of its perfection, totally independent of all comparison with that of others" for "do not nationalities differ in everything, in poetry, in appearance, in tastes, in usages, customs and languages? Must not religion which partakes of these also differ among the nationalities?"

He also predicted that Slavic nations would one day be the real power in Europe, as the western Europeans would reject Christianity, and thus rot away, and saying that the eastern European nations would stick to their religion and their idealism; and would this way become the power in Europe. One of his related predictions was that the Hungarian nation would disappear and become assimilated by surrounding Slavic peoples; this prophecy caused considerable uproar in Hungary and is widely cited to this day.

This question was further developed by Herder's lament that Martin Luther did not establish a national church, and his doubt whether Germany did not buy Christianity at too high a price, that of true nationality. Herder's patriotism bordered at times upon national pantheism, demanding of territorial unity as "He is deserving of glory and gratitude who seeks to promote the unity of the territories of Germany through writings, manufacture, and institutions" and sounding an even deeper call:

In his, Ideas upon Philosophy and the History of Mankind he even wrote, "Compare England with Germany: the English are Germans, and even in the latest times the Germans have led the way for the English in the greatest things."

Herder, who hated absolutism and Prussian nationalism, but who was imbued with the spirit of the whole German Volk, yet as historical theorist turned away from the light of the eighteenth century. Seeking to reconcile his thought with this earlier age, Herder sought to harmonize his conception of sentiment with reason, whereby all knowledge is implicit in the soul; the most elementary stage is sensuous and intuitive perception which by development can become self-conscious and rational. To Herder, this development is the harmonizing of primitive and derivative truth, of experience and intelligence, feeling and reason.

Herder is the first in a long line of Germans preoccupied with this harmony. This search is itself the key to much in German theory. And Herder was too penetrating a thinker not to understand and fear the extremes to which his folk-theory could tend, and so issued specific warnings. Herder's attitude toward Jews is complex. He argued that Jews in Germany should enjoy the full rights and obligations of Germans, and that the non-Jews of the world owed a debt to Jews for centuries of abuse, and that this debt could be discharged only by actively assisting those Jews who wished to do so to regain political sovereignty in their ancient homeland of Israel. Herder refused to adhere to a rigid racial theory, writing that "notwithstanding the varieties of the human form, there is but one and the same species of man throughout the whole earth".