The foundations of the Philosophy of Language were laid by Wilhelm von Humboldt. The principles he advocated have frequently been misunderstood, and some of them have been modified, or even controverted, by more extended research; but a careful survey of the tendencies of modern thought in this field will show that the philosophic scheme of the nature and growth of languages, which he set forth, is gradually reasserting its sway, after having been neglected and denied through the preponderance of the so-called naturalistic school during the last quarter of a century. The time seems ripe, therefore, to bring the general principles of his philosophy to the knowledge of American scholars, especially as applied by himself to the analysis of American languages. The American languages occupied Humboldt's attention earnestly and for many years. He was first led to their study by his brother Alexander, who presented him with the large linguistic collection he had amassed during his travels in South and North America.