sentences:  If the factor "i" were absent, the H matrix would be antihermitian and would have purely imaginary eigenvalues, which is not the traditional way quantum mechanics represents observable quantities like the energy.For a particle that has equal amplitude to move left and right, the Hermitian matrix H is zero except for nearest neighbors, where it has the value "c".If the coefficient is everywhere constant, the condition that "H" is Hermitian demands that the amplitude to move to the left is the complex conjugate of the amplitude to move to the right.