344. If the invocation of illustrious men, of superior spirits, is eminently useful for the instruction they give us, that of ordinary spirits is not less so, though they may be incapable of solving questions of high bearing : by their inferiority they depict themselves, and the smaller the distance that separates us, the greater relation we find to our own situation, without reckon ing that they often give us characteristic traits of the highest interest, as we have explained above, No. 281, in speaking of the utility of special invocations. Here is an inexhaustible mine of observations, taking only those whose lives 'present some peculiarity in regard to their kind of death, age, good or bad qualities, their happy or unhappy position in the world, their habits,' mental state, &c.
With elevated spirits, the range of study is enlarged ; besides the psychological questions, which are limited, there may be proposed to them a great number of moral problems, which extend to infinity on all the po sitions of life, on the best conduct under certain given circumstances, on our reciprocal duties, &c. The value of the instruction we receive on any subject, moral, historical, philosophical or scientific, depends entirely on the state of the spirit interrogated ; it is for us to judge.