From our study of the materials and forms of its expression, it becomes clear how the subject-matter of poetry is the inner life of mood and striving and passionate human action. Emotions may be poured forth in words, and, by means of words, actions may be described. But neither passion nor action appear in poetry as they are lived and enacted; for the poet, working in a medium of words, has to translate them into thoughts. Words cannot embody the real experiences which they express; experience is fleeting and falls away from the words, which retain only an echo of what they mean. Only what can be relived in memory can be contained in a word, and not even all of that; for a word is not a mere embodiment of an experience, but a communication also, and only its public and universal content can pass from a speaker to a hearer. Now, this socialized content of a word is a thought. Even passion the most spontaneous and lyrical has to be translated into thought,--not the abstract thought of scientific expression, but the emotionally toned thought of art, thought which, while condensing experience, still keeps its values. Emotional thought is the substance of poetry. However, albeit an image of the inner life, poetry does not volatilize it into pure feeling as music does, but distinguishes its objects and assigns its causes. Poetry is concrete and articulate where music is abstract and blind. Since words, through their meanings and associated images, can express things as well as man's reactions to them, poetry can also reflect the natural environment of life, its habitat and seat. And yet, because the poet has to translate things into ideas, nature never appears in poetry as it is in itself, but as it is implicated in mind. For the poet, sea and sky, the woods and plains and rivers, birds and flowers, are the symbols of human destiny or the loci of human action. Emotion overflows into nature, but this involves the taking up of nature into man. Not nature, but man's thoughtful life is the poet's theme. If the foregoing statement is correct, emotional thought rather than imagery is the substance of poetry. For poetry, as music with a meaning, can be quite free of definite images. "_In la sua volantade e nostra pace_" (In his will is our peace) [Footnote: Dante: _Paradiso_, 3, 85.] is beautiful poetry, yet there is no image. The thought formulates a mood and finds a sensuous embodiment in musical language, and that suffices for beauty. And yet in poetry, as has been observed, thought tends to descend into imagery. By being connected with a sensuous material, a thought acquires a firmer support for feeling than it could possess of itself as a mere concept. Especially effective is the descent to the lower senses; for they are closest to the roots of emotion. Let me recall again the Shakespearean lyric which I have quoted before in a similar connection, omitting the last lines of each stanza:--