A composite theory of particles is investigated, based on six fundamental; particles (p, n, Λ; ν, e and µ). We assume three types of interactions, very strong, moderately strong and weak interactions (abbreviated as: VSI, MSI and WI), beside electromagnetic couplings. The VSI is global (i. e., completely symmetrical with respect to p, n and Λ), and gives rise to major parts of baryonic mass but is missing among the leptons. This is why leptons are so light. This VSI is also responsible for the creation of various bound states, pions, kaons, etc., from baryon-antibaryon pairs. If there were only VSI, masses of n, p, Λ and those of pion and kaon would be equal. The charge independent MSI splits the mass degeneracies between nucleons and Λ, pions and kaons, etc., and also (eν) and muon. We can conclude that the kaon is pseudoscalar and the λ-Σ and Ξ-N relative parity must be odd, where the Σ or Ξ is the bound state of Λ+ N + N̅ or Λ+ N̅ + Λ. There are open possibilities of existence of baryons and mesons with higher values of strangeness. The Feynmann-Gell-Mann theory of weak interactions can be consistently transferred into our scheme. Finally, the possible existence of extremely weak interactions is speculated (metastability of matter and charge non-conservation).