The Megillah defines the days of Purim as days of feasting (the word used in Hebrew leans much more to the drinking elements of the feast, “Mishteh” [משתה] is similar to the word “Shtiyah” [שתיה] in hebrew) and happiness. The commentators question the redundancy here, since all Biblical days of joy (of which there are generally three - Pesach, Shavuot, Succot) are marked by feasting and drinking.
The Megillah may be hinting to a dual element here in the drinking. Perhaps, by bifurcating the drinking from the happiness it is looking to distill and ultimately enable our achievment of the deepest elements of Simcha. Let’s explore this.

Rambam clearly distinguishes between the need to feast and the need to drink and become intoxicated. He seems to be interpreting the verse above just as we intuited. On one hand there is feasting which by its nature always involves drinking, yet as far as Purim is concerned, drinking becomes it’s own issue. Apparently, in dealing with the issue of “Simcha”, we needed to see drinking - and do some drinking - in its own right, and not as a standard element of the standard festive meal.
But this is absurd! Drinking should somehow bring us to happiness?! Were the sages in those days that base as to ascribe true happiness to drunken stupor?! We’re at an impasse.
Moreover, what is Rambam’s mysterious “falling asleep” from intoxication? This is arguably of the strangest examples of Rambam trying to define an delimit the ambiguities of Halacha. He must be getting at something deeper!

Now Rambam leaves intoxication for the sublimity of altruism! This insane ping-ponging from drunkard to steward-of-kindess is maddening. What is going on here?!?

Rambam is not alone. R’ Yehudah b. Beteira, of the early Talmudic scholars known as Tanaim, also agrees that the road to happiness is paved with alcohol. Huh? Really?
Let’s take a step back. What changed between the era of the Temple and after its destruction as to require an entirely different medium to achieving Simcha? And whatever we respond to this question, It cannot be unintended that the only holiday we celebrate - biblical and not - which was not at a point in history in which sacrifices could be brought was Purim. Which means that the only way to access Purim at that time was through wine. Or perhaps its the opposite, the reason we discovered the joy of Purim was specifically because all we had was wine.

In an astounding analysis, the Ben Ish Hai (19th century, Baghdad) in his book Ben Yehoyadah, sees this statement of R’ Yehudah b Beteira as asserting that we are truly and inherently happy. Wine is the necessity of the times in order to overcome our unbridled anxiety that has nestled its way deep into our subconscious due to the absence of the Temple.
This is an astonishing paradigm. Humanity (or is this only Yisrael...?) is internally happy, happiness is within us always. Our job is, apparently, only to remove that which inhibits its manifestation in our conscious psyche.
What’s truly amazing is that this assertion is already made by Rambam himself:

Read that slowly: “anyone who inhibits themselves from experiencing this joy”. How did Rambam know that everyone already has this joy and only inhibits themselves? Maybe they have never donee anything or experienced anything that should make them happy? Shouldn’t Rambam have written simply “anyone who does not bring themselves to this joy...”?
Rambam can only be saying one thing - we are inherently happy. Are you involved in Mitzvah? Are you committed to Avodat Hashem and love of G-d? You still aren’t happy? You’re simply inhibiting yourself. The fundamental expression of meaning that occurs in the partaking of Mitzvah is such that the internal happiness of humanity must manifest consciously. Only one who is still actively inhibiting is stuck in atitude that is hostile to happiness and has stifled that Simcha that is already their own.
So joy, Simcha, is natural to you, says R’ Yehudah b Beteira, says Rambam, says Ben Ish Hai. You need a bit of wine to overcome the inhibitions? Go for it.
Now the Rambam’s definition of drunkeness - intoxicated to a point of sleep - is wonderful! Anxiety and stress are the leading factors for insomnia and mild insomnia! We all have had those nights where we toss and turn. Rambam is saying that we need to drink such that we can sleep easy, we have detached ourselves from the stressors of life and come back to ourselves. Rambam is so sweet here he just makes us smile.
This is also true regarding his strange regard for the poor. However, this requires a deeper analysis into the nature of Tzedakah which we have attempted to do in our sheets on Rambam’s Hilchot Tzedakah.
But there is something much deeper here. Something that sets this paradigm straight and makes it unique to Purim. This is because the profundity of the application of this paradigm was something that was discovered only through Purim an by none other than Queen Esther herself.
We will analyze but one small, though pivotal, moment in the story, but I assure you that there entire themes runnning throughout the Megillah which develop this concept to unimaginable depth. Regardless, in order to understand what was discovered by Esther thousands of years ago, our modern minds need to hear recent discoveries out of Harvard regarding the nature of the neuro-psychology of happiness, prepare to be shocked.
Before reading the synopsis of these studies, think to yourself: would you ever have thought that you’d be happier buying a pair of shoes from a store with no return or exchange policy versus buying those very shoes for the same price from a store with an amazing return and exchange policy? Dr. Gilbert believes you should have...

Excerpt of Summary from TedTalk,
Dan Gilbert, 2004, “The Surprising Science of Happiness”.
Here’s an old experimental paradigm called the free choice paradigm. 6 objects Are presented to the group - say Monet paintings. The members are asked to rank these paintings from most beautiful to least. Now we give a choice to each person in the group, they can take home a copy of their third or fourth ranked picture, one or the other (Naturally people chose 3 since they had already ranked this higher than 4). When asked later to rerank the pictures, the one they chose (3) nearly always moved up in rank and the one they rejected went down in rank. This has been demonstrated over and over again.
Gilbert and his team decide to take this one step further. They identify a group of Karakoff syndrom patients. Simply, people who drank way too much and can no longer produce new memories. This is called anterorgrade amnesia. The team from Harvard did the same experiment as above, and when they came back to ask them to rerank them, As expected these patients had forgotten the entire earlier episode. Nevertheless they still followed the pattern of ranking the one they chose to take home earlier higher and the one they rejected lower!
They like the one they own without even knowing they own it! The synthesized happiness truly rewired their receptors in terms of ther affective, hedonic and aesthetic reactions to these paintings. Not merely a conscious laziness to cope with what we have, this is how our brains function!
Gilbert went on to develop the next stage of this paradigm. He and his team performed another experiment at Harvard. They created a photography course and taught the students how to use a darkroom. The students went around campus and took twelve photos of things they really wanted to have memories of and came to develop them in the darkroom. They brought their cameras, set up a contact sheet and figured out which were the two best pictures they’d like to keep.
When they’re finally developed and beautiful, they were asked “which one would you like to keep? The other needs to stay with us for records.” The student were divided up into two groups, one was told that they have four days to swap it out and change their mind. The other group was told they will not be able to change their mind.
Additionally, half the group was told to predict whether they will be happy with their picture that they chose, the other half is merely measured in terms of how much they like their photo over the next 3-6 days. The predictions envisioned that regardless of whether one was part of the irrreversible group or the reversible one, their level of happiness would be similar.
Turned out that the predictions were incredibly off, and the people who were in the irreversible group liked the photo they had chosen a lot! And the ones in the returnable group have killed themselves over it and even once thee time to return it expires they still don’t like their choice.
Then the Harvard researchers ran a similiar experiment where they asked which course would you rathr be in, the one where you can have a returnable picture after 4 days, or the class that you cannot reneg on your decision. 2/3 of students wanted to be in the course where they could change their mind. That means that 66% of students chose a course in which they would be far less happy and satisfied!

What Gilbert ultimately proved was that our brains have adaptive processes which allow us to be happy with our lives and the world around us. This was clearly a neurological response as was evident by the group of amnesiacs. He then proved that this adaptive process only works when we are bounded in our choices. The moment we feel that there is more outside of what we have been given, we lose our ability to synthesize happiness and we remain morose. This is astounding! This is everything the sages above meant when they asserted that we are all internally happy. This is literally how our G-d given minds evolved such that we become the source of our own happiness - but only when we accept ourselves in our unique positions within space and history.
Our mouths drop when we now turn our attention to our beloved Queen Esther:

The message is clear. When we recognize the nature of our own opportunities and the uniqueness they provide, we begin recognizing the potency of our own self worth. The brain literally adapts into a state of happiness as it consciously discovers the incomparability of “myself, in this moment”. So long as happiness remains an external gem to be mined elsewhere, it remains elusive. The moment we come to appreciate the G-d given opportunities that are inherent in our existence itself, we cannot escape happiness.
That is why when Esther views Ahashverosh negatively - as a dog! - she still believes that there is another way of expressing herself and that she’d be happier doing things that other way. Perhaps sleeping with Mordekhai again instead of this idiot of a king. At that moment, G-d leaves her - “the Divine presense left her”. G-d cannot reside with someone who has not yet accepted who they are where they are. As the Talmud says, the divine presence is not found wherever there is no joy - Simcha.
The moment she accepts her place in the fabric of existence as needing to be the one to go sleep with Ahashverosh, she views him as her lion, and G-d returns to her once more.
Are we still looking for a diamond called happiness? Or have we figured out that we are the diamond? Will we be of the 66% who chose the photography class that leads us away from happiness? Can we come to terms with the realities of Esther’s discovery? Maybe a little wine may help...
Sometimes we are afraid to be locked into a given path in life. On the other hand, the discovery of the path one must take in order to be oneself is the only way to truly unlock the inherent happiness latent in the neurology and souls of every individual.