The second volume of this series is devoted to the Proceedings of the Second Anniversary Symposium under the chairmanship of the Niels Bohr Visiting Professor of the year - Professor L. Rosenfeld, Deputy Director of NORDIT A, Copenhagen, and the Editor of Nuclear Physics. With particular appropriateness, the Symposium was inaugu­ rated by the Honorable C. Subramaniam, Union Cabinet Minister, the founding father of the Institute. The meeting was characterized by two features: (1) the enlargement of the scope of the discussions in theoretical physics, with the inclusion of many-body problems and statistical mechanics! (2) Seminars on pure mathematics, stimulated by the prdence and participation of Professor Marshall H. Stone of Chicago as the First Ramanujan Visit­ ing Professor at the Institute. The year 1963 marked a new stage in the development of high­ energy physics - the first successes of SU (3) symmetry and the eight­ fold way had such an impact on the scientific world that the hard, unyielding domain of strong interactions was now again open to ex­ ploration. The volume opens with two significant lectures by Sudarshan and O'Raifeartaigh on fundamental problems relating to internal sym­ metries. The theory of Regge poles, after its initial triumph, met with rough weather, the nature and intensity of which can be realized from the series of discussions in this volume.