Introductions can be short or long, weak or strong, perfunctory or in-depth.
Professor Mark Schorer's introduction to the Rinehardt edition of Wuthering Heights, first printed in 1950 and reprinted in 1960, posits that Emily Bronte was trying to figure out if it was possible for the strength of an unmoral passion to possess its own morality. When I read his introduction for the first time, in 1973, I was sure I understood what he meant. He meant, I believed, a passion that injured, even killed others associated with those who felt it and acted on it/expressed it.
41 years later, I am not so sure.
Now that I am older, I am not so sure that passions themselves carry any kind of morality, or lack. They are very strong feelings. The morality, which concerns social conduct, inheres in ways in which the holders deal with these feelings. Morality is intimately associated with different kinds of laws tacit and written. If I feel passion for a piano and write a poem about this passion, I am expressing my passion without breaking any of our written laws. (That is, if the poem does not recommend or emphasize the idea of hurting or killing someone in order to use or admire the piano,) If instead of writing a non-violent poem, I kill someone who is playing the piano, I have broken the laws of my state and country. However...the passion itself is not immoral or moral. My expression of it is because our morality is bound up with our written laws. Other people have passions for pianos and do not kill those who are playing them.
Similarly (although it may seem a bit bizarre to compare the passions felt by Catherine and Healthcliff to my supposed passion for a piano), I do not see Catherine's and Heathcliff's passion for each other as unmoral. Perhaps the laws of our respective lands -even in the 1940's- rendered passion they experienced as unmoral because it and they did not seem to take into account that they were both married to other people, but felt much much more strongly for each other, Not against our laws, but against the unwritten laws of kindness and civility, they acted cruelly to others who seemed to get in the way of their expression of this passion.
Now if they had both run away at some point to an island or another country before either of them had married, I don't see that anything about even the expression of this passion could be considered unmoral. The unmoral nature of the passion in Emily Bronte's time would seem to concern itself with Catherine's marrying Linton so that she could use his money and position to advance Heathcliff's standing. This to me would seem to indicate that they were committing a kind of adultery, which is of course against the law in certain areas, even now. However, it is only unmoral if we believe that this law is just, which I don't.
In short, it seems to me that Professor Schorer has labeled their passion unmoral because it flouted certain written laws. I must conclude that he agreed with those laws in order to frame it thus.
And thus, although I admire Professor Schorer's effort to explain Emily Bronte's reason for writing Wuthering Heights, I now question its validity.