The Rubai is a simple quatrain but extremely complex because it must explain its entire nature within the two lines. In another word, the book starts and ends with a two-line stanza. The rhyming of Rubai is AA, bA
A Rubai is a type of poem that is a Persian verse poem. For this type of poetry, each stanza of the poem is a quatrain. Because of this, lines one, two and four rhyme where line three usually does not. This form of poetry is the most popular in middle eastern countries such as Iraq. A rubai poem could be written about nearly any topic as long as it follows the verse laws and stanza rules of such.
Many people write heavy messages of humanity with this style of poetry. This is a very common type of poetry, especially in the middle eastern countries where it was founded. Many modern poets tend to use the rubai poetry style and as such, it has been studied extensively. This type of poem is rather expressive, and as long as the format is correct, nearly any poem could be considered Rubai as long as the stanza and verse rules are correct.