Irrational number number to ratios of continuous magnitude. In his commentary on Book 10 of the "Elements", the Persian mathematician Al-Mahani (d. 874/884) examined and classified quadratic irrationals and cubic irrationals. He provided definitions for rational and irrational magnitudes, which he treated as irrational numbers. He dealt with them freely but explains them in geometric terms as follows: In contrast to Euclid's concept of magnitudes as lines, Al-Mahani considered integers and fractions as rational magnitudes, and square roots and cube roots as irrational magnitudes. He also introduced an arithmetical approach to the concept of irrationality, as he attributes the following to irrational
What Work Is Fame" and "Growth" are direct accounts of two of Levine's jobs as a young man. "Fear and Fame" is based on a job Levine had cleaning out and refilling acid vats in his mid twenties. "Growth" is about the job Levine held at a soap factory at the age of fourteen. Many of Levine's poems are based on his experience growing up in Detroit. The titular poem, "What Work Is", is based on Levine's experience of waiting in a Detroit employment line. "The Right Cross" is related to a boxing teacher who taught Levine to defend himself while growing up