In that time were made those things that afterwards were most renowned of all the works of the Elves. And Fëanor, being come to his full might, was filled with a new thought, or it may be that some shadow of foreknowledge came to him of the doom that drew near; and he pondered the nature of the Quendi. Those who live in the space between that of the Ainu, born from the thought of Illuvatar, who glory in the music of creation. And the Atani, the aftercomers, born to Middle-earth and of Middle-Earth, not made for the blessed realm. But Quendi, named by words, makers of words, bound by their words and givers of words, carried within them Illuvatar's song of creation, yet also possessed some of the nature of the aftercomers, which was to strive.
So, from the Eldest Speech of the Ainu, from the languages of his people, from the sounds of birds and beasts, Fëanor drew. From the lessons of Manwë, who delights in words, from those of Aulë, who delights in the making of all things, and even of Melkor, who always seeks to twist and change the substance of creation. He forged all these into a form, and crafted a language, speakable by the tongues of Elves and even Men, yet which can speak of all the things of Eä. And this work, drawn from the speech of the Ainu, could harmonize with the melody of creation, and resonate with it.
But Fëanor, being never satisfied, had wrought this work with one change in mind. Of the concepts woven into this language, the subtlest and greatest he took not from Manwë, nor Aulë, or even Melkor, but from Yavanna, of all growing things. And to the time before thought, the spaces between words, the silence after an utterance, he tied the meaning <thrive/flourish/prosper>.