What did Siddhartha really meant by ending suffering

Approach this on two levels, the doctrine level:

Desire is suffering. The 8-folds Paths helps you to end desires. There are Arahants that have ended desire hence ended suffering. Therefore it is possible to end suffering. Having said that, this doesn't mean you can do it in one life-time, as a human or other beings in other realms. Everything still depends on your parami from your many pass lives, your kamma, your practices, your free will to make decisions and judgments, and so forth.

The metaphysical/conceptual level:

When you mention desire, yes - the human realm is "Desire driven". In the Buddhism universe, there are realms different to the human realm and not driven by desire. If you have reached a certain stage of enlightenment, even not fully enlightened, you may/may not reincarnate into a realm/world that is not driven by desire. So, ending the desire in the human realm is possible. Otherwise, the idea about other realms would be impossible which contradicts to pretty much all of the concepts of Buddhism universe.

If you (the mind) has sexual lust; this in reality is a form of tension, torment & suffering. When you find another person to relieve you of your sexual tension by engaging in the sexual act; this is pleasurable; this is a (temporary) release.

Similarly, when a meditator can calm and end sexual tension using meditation; this is pleasurable; this is a (permanent) release.

OP: ... once you satisfy some particular need, since you are a human being, other needs will arrive and with that new forms of suffering, but then I wonder, how is it possible to end suffering if we will always desire for certain things, as long as we exist in this material world?

Feeling the physical sensation of hunger, which arises from a purely biological reaction, leads one to crave for food. This craving is satisfied once you eat food.

But craving doesn't stop there. It leads to clinging or attachment. While you are eating, if someone tries to snatch your food away, you become angry. If you truly enjoy a certain food, you would long for it when it's not there, even when you're not hungry. The food that you enjoy eating, for e.g. chocolates - you might keep it hidden and avoid others from taking it away. Also see: "What is the difference between craving and clinging?"

Dukkha or suffering or dissatisfaction is your experience of being separated from what you enjoy, or encountering that which brings you pain, or not being able to get what you want. This is the first noble truth.

Dukkha is caused by craving. That's the second noble truth.

To end dukkha, you must end craving. That's the third noble truth.

You have asked a very good question, because your question implies that suppression of craving is the way to end suffering. That's a very good idea. The Buddha tried it too in the form of extreme asceticism, nearly starving himself to death, but found that it did not work. He said that if the string of a violin is made too tight or too loose, it won't produce music. The string of a violin must be adjusted just right. Similarly, ending craving is neither possible through overindulgence in craving, nor suppression of craving. This is also known as the middle way.

The answer to your question comes in the form of a journey from the third noble truth to the fourth noble truth.

The way to end craving (the fourth noble truth) is the noble eightfold path, which is a gradual path that ultimately leads to the perfection of wisdom. I discuss the gradualness of the method of practicing the noble eightfold path in this answer.

The enlightened one, perfected in wisdom, feels the sensations of hunger, but does not crave food. He nevertheless eats for sustenance. He does not lust after food. If he does not get food, it will not make him unhappy or agitated. Feeling hunger is different from craving for food. His perfection in wisdom leads him to be able to see through his experiences and not become overwhelmed by them.

I wonder, how is it possible to end suffering if we will always desire for certain things

But then on the other hand, if one doesn't have any desire whatsoever, even the wholesome desire to end suffering, then one won't go anywhere. See Ven. Ananda's "going to the park" simile in SN 51.15 for more details.

It's kinda super-straightforward. If you keep thinking that whatever your life looks like is WRONG because you're lacking something or on the contrary, because it has something you don't want - as long as you keep thinking like that, you're unhappy (aka suffer). Whenever there's this mental conflict between IS and SHOULD, there's suffering. Once you learn to keep the two in sync, there's no suffering for you. That's it. It's all about the way our mind evaluates the experience.

Is it possible to keep IS and SHOULD in sync? Yes, absolutely. It's all in your head, isn't it?

I mean, you can have plans, sure - but a healthy plan is different from a bitter SHOULD, see what I mean?

What did Siddhartha really meant by ending suffering

I sort of understand "happiness is inside of you" -- but I think that's a result of applying Buddhist doctrine (see e.g. this question with this answer) -- that phrase is a description of an effect of doctrine, it isn't the doctrine itself -- and if I didn't know the doctrine (which you say you don't, "I'm really naive into buddhism") then I don't think I could understand how it works.

I might mention there are different schools of Buddhism with different ways of explaining things; but you're asking about how Gautama Buddha explained it so I'll try to answer that.

Regardless of what he 'really meant', a canonical version of what he 'really said' is the so-called "four noble truths" -- so it's up to us to read (or hear from a teacher) what he said and then understand that for ourselves.

Here is a version of the sutta in which he describes the four noble truths: Dhammacakkappavattana Sutta -- Setting in Motion of the Wheel of Dhamma. The English is on the right-hand side, and words (like dukkha) which don't have an easy/obvious/single-word translation are left in the text as-is with a hyperlink to a dictionary entry (like this one). I like that because normally, when you translate something, you have to translate one word into another word, which loses some/several of the meanings of the original word.

If you want a simpler (word-for-word) translation, see e.g. here or here.

To paraphrase:

1. What he means by "suffering" or "unsatisfactoriness" is more-or-less defined in the "first noble truth", e.g. the following are included in the list of what's unsatisfatory: birth, old age, sickness, death, association with what's disliked, separation from what's liked, not obtaining what's liked, the aggregates of attachment.

   Elsewhere it's said that "all compound things" are impermanent and dissatisfactory.

2. The cause of this "suffering" is "craving"

3. The cessation of "suffering" is the cessation of "craving", it's freedom from craving, it's dispassion

I guess there are endless objects of craving:

• Sensuality (sexuality, music, pictures, tasty food)
• Social status (money, fame, praise)
• Physical security (money, health, youth, housing)
• Spiritual state (peace of mind, certainty)

I constantly hear from buddhists that "happiness is inside of you"

I interpret that as "unhappiness is craving what's outside of you" (plus some understanding that there is no real self, so all craving is "outside").

Happiness (in contrast) is cessation of, detachment or disassociation from that craving.

The word for craving is also, I think, literally, thirst.

how is it possible to end suffering if we will always desire for certain things, as long as we exist in this material world?

Canonically the way to end suffering is the fourth noble truth, which says that it's the "noble eightfold path" -- which may be summarised as the Threefold Training.

Regarding the "material world", perhaps that's defined by Buddhism Middle Way doctrine:

... the middle way of moderation, between the extremes of sensual indulgence and self-mortification:

Monks, these two extremes ought not to be practiced by one who has gone forth from the household life. There is addiction to indulgence of sense-pleasures, which is low, coarse, the way of ordinary people, unworthy, and unprofitable; and there is addiction to self-mortification, which is painful, unworthy, and unprofitable.

So monks are expected to need (and to ask for) what's "needful", what's "necessary for the holy life" -- basically clothing, food, lodging, and (when sick) medicine -- maybe small sundries like an alms bowl, razor, toothbrush, sewing kit. It's not meant to be luxurious (clothing is strips of ochre cloth, food is whatever they're given and not after noon).

So by limiting what they're allowed to what they need, I suppose that monks can get used to not craving for what they don't need.

The situation may be more complicated for laypeople -- more "temptations", more "responsibilities" -- I suppose that's why some people (including Gautama Buddha himself) "go forth" (i.e. leave the householder's life and become homeless).

Even so I think that a little insight (e.g. as provided by an understanding of Buddhist doctrine, including the four noble truths) is better than none -- e.g. even if suffering keeps recurring (as a result of craving's recurring), it's helpful (and you may experience "internal happiness" as a result of) understanding their cessation.

I haven't mentioned "virtue" which is important -- I think that breaking the precepts (e.g. killing, lying, stealing) causes suffering, and (conversely) behaving ethically does (or helps towards) the opposite.

Also there are "afflictive emotions" (greed, anger, jealousy, pride, and so on) that a Buddhist might try to avoid.

But aren't the conditions of unsatisfactoriness basic human needs like hunger or physical pain?

Consider music, for example:

• If you don't like it then it's "unsatisfactory" to hear it (it's "association with what's disliked")
• If you like it then it's "unsatisfactory" to stop hearing it (it's "separation from what's liked")
• If you want to hear it again and can't, that's "unsatisfactory" too (it's "not obtaining what's liked")
• If you want to hear it again and can, that may be habit-forming, and only delaying or increasing the eventual "unsatisfactoriness", also maybe immoral and with unpleasant consequences (if you neglect your duties, and spend time, money, and/or attention on the new habit)

Ditto almost any other pleasure or desire. Hence trying to distinguish what's "needful" and to avoid "attachment".

How could we end dukka by any means other than satisfying or need for food or medicine?

Note that people die, sooner or later ("old age, sickness, death"), even with food and medicine.

Food and medicine may be "necessary" ("for the holy life"), but impermanent, maybe unreliable, not a "refuge". Food for example will last a day, and then what?

Another way to understand "happiness is internal" might be "happiness is mental" or "happiness is mind-made" -- perhaps it depends more on mental factors (like the following) rather than on physical possessions:

• Remembering good that other people have done
• Training your mind to abandon craving
• Remembering good that you've done
• Having kindly (rather than hostile, selfish) emotions towards others

"Ending suffering" is a red haring caused by older translations of the Pali word Dukkha.

It is a word which has not survived in Western Indo-European languages, but its antonym "Sukkha" is the root for our word "Sugar" in English, "Sucre" in French and "Zucker" in German, all meaning "sweet".

Later translators preferred to either leave the term untranslated or to clarify that translation with terms such as anxiety, distress, frustration, unease, unsatisfactoriness, etc. Many contemporary teachers, scholars, and translators have used the term "unsatisfactoriness" to emphasize the subtlest aspects of dukkha.

Buddhism focuses on developing insight into the nature of dukkha, the conditions that cause it, and how it connects & affects us all. This insight, bodhi is (also dubiously) translated as enlightenment. So what Siddharta actually meant would be closer to "ending the arising & conditions of unsatisfactoriness in one's mind", which also creates positive effects in reality (by actions based on understanding) and therefore to others.