It is the purpose of the present paper to discuss the intuitive meaning and the interrelations of various coefficients of the Ising model. Thus, the intuitive meaning of blm and b̅lm, the coefficients of cluster sums, is explained. Van der Waerden-Oguchi's expansion is generalized to the case with magnetic field and the coefficients Ωnm is defined and its meaning is explained. The equivalence of the calculation of the susceptibility with zero field and the non-crossing chain problem is proved. And a method of evaluation of these coefficients is proposed which requires least labour of counting the graphs by using the decomposition of Fuch's coefficients γk. The data our calculations are listed in the Appendix. From these data an outlook of this problem to the future and the theory of the imperfect gases are discussed.