hard-core interaction. It is necessary therefore that any bound state of a pair of atoms ψ ( r ) have a node in the wave-function at the relative co-rodinate r = 0. The radial part of the pair wave-function must therefore vanish as ψ ( r ) ∝ r $^{ℓ}$, and so the bound-state must be in the ℓ -th angular momentum. It follows from Pauli-principle that even ℓ ’s have total spin zero, i.e. a singlet state, while the odd ℓ ’s have spin 1, i.e. a triplet state. The idea of a finite angular momentum pairing for He 3 therefore arose [50]. Following Berk and Scrieffer’s [51] result that ferromagnetic fluctuations are deleterious for s-wave pairing, Layzer and Fay [52] suggested that such fluctuations may promote spin- triplet ℓ = 1 pairing. The discovery of such pairing in liquid He $^{3}$, (for reviews, see 3, 53), led to further theoretical ideas and calculations. It is generally agreed that although the idea of exchange fluctuations give the correct symmetry of pairing, weak-coupling calculations based on the idea do not work quantitatively. Calculations properly taking into account the short range repulsion between the He atoms and estimating interactions with constraints put by the measured Landau parameters give the right scale of T$_{c}$ and its pressure dependence [54]. In the late 1970’s superconductivity in heavy fermions was discovered [55–57] and more superconducting heavy fermions continue being discovered. In these materials, the mass enhancement of the fermions is of O (10 $^{3}$), so that the effective fermi-energy is of the same order or smaller than the characteristic phonon energy. It was suggested that in this case the phonon attractions could not overcome the Coulomb repulsion because the concept of the Coulomb pseudo-potential is invalid and therefore the pairing must be in a finite angular momentum state [58]. Experiments were suggested to test this suggestion which were soon carried out [59]. Transport experiments were analyzed [60, 61] and they could only be understood if there was a line of zeroes of the gap-function on the fermi-surface. Such a gap function is not allowed [62, 63] in the spin-triplet manifold in the presence of spin-orbit scattering. Therefore ℓ = 2 pairing was to be expected. At the same time, it was known that the heavy fermion superconductors were close to anti-ferromagnetic instabilities. This led to an investigation of pairing through anti-ferromagnetic fluctuations which we have reviewed above [19] which has since been much used (and in my view abused) extensively in connection with the superconductivity in the Cuprates. A concurrent RPA calculation [64] of the pairing susceptiblity in the Hubbard model also revealed a tendency to d-wave pairing. 32