Accordingly the responsion, thus conceived of, is the formal expression of this relation of two or more strophes to one another. Where the principle of the responsion is strictly carried out each line of the first strophe corresponds to the corresponding line of the second, either _verbally_ or _substantially_, and in the latter case either by _parallelism_ or _antithesis_. The similarity of the majority of lines which thus correspond throws the differences at certain points into strong relief and renders them all the more forcible and impressive. The highest organic structures have been analysed and found to be built up from a single cell. All the preliminary conditions which enable the cell to form organisms lie dormant in it already, but the germ cannot become an organic being except by a slow process of development. What we now have to do is to find the germ from which the responsion has developed; and the germ of this phenomenon is the _parallelismus membrorum_ which constitutes the vital element of apothegm and verse in the Semitic languages, and more particularly in Hebrew. But two things may be parallel one with another not only by analogy but by contrast. The _parallelismus membrorum_ places side by side two or more ideas, analogous but not identical, and adapted by their slight diversity to give an image of what the poet desires to convey. Such sentences abound in the prophetic discourses, as in Isaiah i. 3, The ox knoweth his owner, and the ass his master’s crib: But Israel doth not know, my people doth not consider. And Amos ix. 2, Though they dig into hell, thence shall my hand take them; And though they climb up into heaven, thence will I bring them down. The idea, being presented under a different figure, is repeated without producing an effect of tedium or monotony. What the _parallelismus membrorum_ is to the verse or sentence, that the responsion is to the strophe or discourse. By slight variations on the responsion two literary forms were evolved to supply an æsthetic want. When two strophes stand in such a relation that the conclusion of the one answers to the beginning of that which succeeds it, the result is the _concatenation_, which unites two strophes with one another and leads the way from one field of thought to another. Again, if the beginning of one strophe or group of strophes corresponds with the conclusion of the same, the result is the _inclusion_, the object of which is to emphasise the logical and æsthetic unity of the said strophe or group of strophes. An example of concatenation may be cited from Isaiah, Chap. i. One column begins-- _Hear_, O heavens, and _give ear_, O earth, for the _Lord hath spoken_-- and ends-- We should have been as _Sodom_, we should have been like unto _Gomorrah_. The second strophe-column begins-- _Hear the word of the Lord_, ye rulers of _Sodom_; Give ear unto the Lord our God, ye people of _Gomorrah_.