It's very hard to carry the message in AA, because counter-messages abound. Poor newcomers! No wonder people are so confused.
Let's look at the notion of insanity. I was at a meeting recently where someone declared (and others agreed) that drinking the second and subsequent drinks constituted 'the insanity of alcoholism'.
Nowhere in the Big Book does it use the notion of insanity to describe what happens after the first drink. Au contraire: this is presented as an automated process with physical foundations, over which processes of reasoning are powerless. This physical craving for the second and subsequent drinks is not an example of failed reasoning or irrationality but an example of compulsion over which the individual has little or no control. Reasoning, sane or insane, is simply not involved.
Cf. The Doctor's Opinion:
They took a drink a day or so prior to the date, and then the phenomenon of craving at once became paramount to all other interests so that the important appointment was not met. These men were not drinking to escape; they were drinking to overcome a craving beyond their mental control. (My emphasis)
In the basic text part of the Big Book, the terms insane and insanity are used three ways: firstly, as a subjective description of how a drunk alcoholic's behaviour appears to others.
He is always more or less insanely drunk.
Secondly, there are several references to Korsakoff syndrome, namely the wet brain phenomenon at the late stages of alcoholism (read this and this):
When this sort of thinking is fully established in an individual with alcoholic tendencies, he has probably placed himself beyond human aid, and unless locked up, may die or go permanently insane.
Rumor had it that he had been committed for alcoholic insanity.
Sometimes there were screaming delirium and insanity.
All other references, however, are to the insanity of having the first drink, which, it should be recalled, occurs when the individual is sober. That's all.
But there was always the curious mental phenomenon that parallel with our sound reasoning there inevitably ran some insanely trivial excuse for taking the first drink. Our sound reasoning failed to hold us in check. The insane idea won out.
In some circumstances we have gone out deliberately to get drunk, feeling ourselves justified by nervousness, anger, worry, depression, jealousy or the like. But even in this type of beginning we are obliged to admit that our justification for a spree was insanely insufficient in the light of what always happened.
However intelligent we may have been in other respects, where alcohol has been involved, we have been strangely insane.
Then came the insidious insanity of that first drink, and on Armistice Day 1934, I was off again.
Yet all reasons for not drinking were easily pushed aside in favor of the foolish idea that he could take whiskey if only he mixed it with milk! Whatever the precise definition of the word may be, we call this plain insanity. How can such a lack of proportion, of the ability to think straight, be called anything else?
I rather appreciated your ideas about the subtle insanity which precedes the first drink, but I was confident it could not happen to me after what I had learned.
The insanity of alcohol returns and we drink again.
Again it was the old, insidious insanity—that first drink.
To be clear: if a drink can lead to a bout of days, weeks, months, or years, with all the attendant difficulties and loss of control over the course and content of one's life (= unmanageability), to have that drink is insane.