"Theme and variation" usually refers to music but it is also an aspect of poetry. We find it in alliteration (repetition of consonants), assonance (repetition of vowels), and rhyme. It is a statement of a "theme" -- a consonant, vowel, or group of sounds -- and then a restatement in a slightly different way. For instance, in a rhyme of "cat" and "bat," the theme is the first word, and the variation is in the substitution of "b" in "bat" for "c" in "cat."

In music, theme and variation is a way to develop a simple melodic or rhythmic idea into a full musical composition. The theme and variation of the melody binds the piece together in the same manner in which a rhyme in poetry binds the poem into a unit and provides consistency and completeness.

In our own lives, we have theme and variation. On the face, we all present the same theme of nose, two eyes, a mouth, and various other parts -- but the arrangement differs with each person.

Our life is a theme -- and our particular actions are variations on that framework.

Trees are variations on the root-trunk-branch-leaf theme.

When we use theme and variation in poetry, we can develop an idea as a restatement of the same idea on different levels of symbolism, or in different depths of our own understanding, or in different shades of our emotional response.

There are other types of theme and variation. For example, in Indian music, a sitar soars in melodic flight, while a tambour plays a drone -- a constant sound that varies rhythmically but maintains the same pitch. It's said that the drone represents the constancy of soul, while the sitar's melody sings in analogy to the changing patterns of life on earth.

In poetry, there are constants and variables, like themes and variations in music. The constants are psychological resting points, so that we can experience a sense of finality while we manipulate a course through the form of the poem. One constant is the rhyme; it is something that anticipate, and something that satisfaction when we find it. Because the rhyme is constant, we experience it as a rhythm, like the rhythm in music.

Some people find modern music uninteresting (and even repelling) because of its lack of apparent rhythm. The mechanical mind can't make sense of it, because there are no logical reference points (like phrasing and rhyming), and there is no constant drone of touchable reality under it all. We dislike the same type of chaos when we find it in our own lives.