  We explore the relationship between the SU(2) sector of a general integrable
field theory and the all-loop guess for the anomalous dimensions of SU(2)
operators in N=4 super Yang-Mills theory. We demonstrate that the SU(2)
structure of a nested Bethe ansatz alone reproduces much of the all-loop guess
without depending on the details of the particular field theory. We speculate
on the implications of this for strings in AdS_5 X S^5 being described by the
multi-particle states of an integrable worldsheet theory, and relate the
techniques here to the known relationship between the Hubbard model and the
all-loop guess.
