  The spin half Heisenberg antiferromagnet on the Kagome lattice, is mapped by
Contractor Renormalization to a Spin-Pseudospin Hamiltonian on the triangular
superlattice. Variationally, we find a ground state with columnar dimer order.
Dimer orientation fluctuations are described by an effective O(2) model at
energies above an exponentially suppressed clock mass scale. Our results
explain the large density of low energy singlets observed numerically, and the
non magnetic T-squared specific heat observed experimentally.
