The atomic and bond fragilities are two types of indicators for observation the individual atoms, the natural components of any reacting system. As demonstrated on the example (p. 6.5), they describe convincingly the degree of coupling of an atom in a particular position in a molecule, not only by a bond to particular neighboring atom, but through the electronic interactions, to the complete network of atoms in the entire system. Together with the squares of the normalized atomic coefficients of the eigenvectors they provide most valuable information on the role of every atom in the transition process from reactants to products.