  We report on a nontrivial bosonization scheme for spin operators. It is shown
that in the large $N$ limit, at infinite temperature, the operators
$\sum_{k=1}^N \hat s_{k\pm}/\sqrt{N}$ behave like the creation and annihilation
operators, $a^\dag$ and $a$, corresponding to a harmonic oscillator in thermal
equilibrium, whose temperature and frequency are related by $\hbar\omega/k_B
T=\ln 3$. The $z$ component is found to be equivalent to the position variable
of another harmonic oscillator occupying its ground Gaussian state at zero
temperature. The obtained results are applied to the Heisenberg XY Hamiltonian
at finite temperature.
