Let me illustrate with an example. We should be thankful for a commentary upon "Faust" which traced back all the diverse material of Part II. to its historical sources, or for a psychological analysis of Part I. which pointed out how the dramatic conflict corresponds to a personal conflict in the soul of the poet; we should be glad of an exposition which pointed out how this subjective conflict is itself based upon those ultimate and universal human things which are nowise foreign to us since we all carry the seeds of them in our hearts. Nevertheless we should be a little disappointed. We do not read "Faust" just in order to discover that also we are, in all things, "human, all too human." Alas, we know that but too well already. Let any one who has not yet learnt it go for a little while out into the world and look at it without preconceptions and with open eyes. He will turn back from the might and power of the "too human," hungrily he will pick up his "Faust," not to find again what he has just left, but to learn how a man like Goethe shakes off these elemental human things and finds freedom for his soul. When we once know who was the "Proktophantasmist," to what chronological events the mass of symbols in Part II. relates, how it is all intimately bound up with the poet's own soul and conditioned by it, we come to regard this determination as less important than the problem itself--what does the poet mean by his symbolic creation? Proceeding purely reductively, one discovers the final meaning in these universal human things; and demands nothing further from an explanation than that the unknown and complicated shall be reduced to the known and simple. I should like to designate this kind of understanding as _retrospective understanding_. But there is another kind of understanding, which is not analytic reduction, but is of a _synthetic_ or _constructive_ nature. I would designate this _prospective understanding_, and the corresponding method as the _Constructive method_. It is common knowledge that present-day scientific explanation rests upon the basis of the causal principle. Scientific explanation is causal explanation. We are therefore naturally inclined, whenever we think scientifically, to explain causally, to understand a thing and to regard it as explained whenever it is reduced analytically to its cause and general principle. In so far Freud's psychological method of interpretation is strictly scientific.