The Dukka (translated as 'suffering' in English) explained by Lord Buddha in Dukka Ariya Sacca is not the sorrow we feel due to hardships, etc. in day to day lives. Even non Buddhists are aware of such things, and you don't need a Buddha to explain it. The Dukka Ariya Sacca described in 4 Noble Truths, refers to a much deeper concept. This is elaborated in Saccavibhaṅgasutta (aptly named as it means to elaborate the truth).
As someone who studied Dhamma in my native language, I find it quite difficult to explain this in English. This is one of the most subtle and deep portions of Dhamma. So, you should do your own research and study in order to understand Dukka properly. Please excuse me for the long answer, but I don't think summarizing is possible without destroying the meaning.
Lets take the eye for an example;
Your eye receives a picture (bunch of photons). When this picture is received, and it is combined with the mind, to result cakkha vinnana which results vedana (sense), Saññā(signal), Saṅkāra, vitakka and papanca. (Refer: Madhupiṇḍikasutta for more details).
This process results us building a world around us. Which is not the reality. In this interpretation, when you see things, lets say your house, your family, your kids, etc. it results the view of 'nicca' or constant/permanent world around us. Lord Budhdha explains to us about the view of 'anicca' (non constant or impermanent view), which helps us see through this bubble we have built around us. Anicca in this context means; effects will cease to exist, when the causes for those effects are ceased (93. Dutiyadvayasutta). Personally, I view this as an explanation of a process rather than a 'thing'. We deceive ourselves (moha) by interpreting this process as a constant world, and convince ourselves that there is a 'self' that perceives that world.
Take for an example, a man comes in front of you.
- If you are a parent of that man - your see a son.
- If you are married to that man - you see your husband.
- If you are one of his kids - you see a father.
- If he a friend of yours - you see a friend.
- If you are holding a grudge against him - you see an enemy.
Did the man change from occasion to occasion or person to person? did the photons that traveled from his body to your eyes changed in these occasions? Everyone saw the same man, but each party interpreted that picture differently, based on the associations formed in their mind. Like this, we only feel our mind. The picture from outside is just a helping stimulus. The feeling, the reality we build in our mind is personal to us. Based on the abstraction we have built up in our own mind, we generate attachments; ether lobha (attraction), dosa (repulsion) or upekhā (neither attraction nor repulsion). This is the reason, while the parents, wife, kids may love the man in the above example, the person who holds a grudge views the same man as an enemy. Man's picture that has met their eyes were evaluated against different abstractions, and placed in different characters in each receiver's world. None have see the man, everyone had seen a reflection of their own mind. And we constantly try to find happiness in this made up world.
Let me prove that this conceptual world is personal to us. Lets say a homeless person who have not had a meal in days received a Pizza. How would it taste to him? Could be the best Pizza he ever had. A billionaire is given the same Pizza to eat. He would view it as 'crappy food' and even reject it. That same billionaire gets kidnapped and thrown in a room where he have to starve for days. Would he view the Pizza with the same contempt after being starved? Did the Pizza change? Why did the Homeless man and Billionaire view the same Pizza differently? Its because their conceptual worlds are different. Why did the same Pizza was viewed differently by the Billionaire before and after starvation? Its because the concepts in his conceptual world changed.
While we live in our conceptual world, in the reality the picture that stimulated the eye is no more. The picture of the man has met our eye, generated a stimulus and ceased to exist in that form. This is why Lord Buddha teaches us 'cakkhu aniccaṁ' - eye is impermanent. But in our conceptual world we see a Son, a Husband, a Father, a Friend or an enemy (a person) who continues to exist. None of those classifications came to us with the picture of the man that met our eye. All that is assigned by our own mind. Concepts associated to the external stimulus builds the conceptual world that each person lives in. The main reason behind building this conceptual world is to ascertain yourself that 'you' exist. The logic is simple; 'because I see the world, I exist'.
'Ditto dittamattam' - What you see is simply a picture. It ends then and there. 'vinñāṇaṁ vinñāṇaṁattam - What you learned or 'got to know' (as a result) ends there. The reality is that these are two processes. Since the causes of these cease to exist, their effects cease to exist too. Its us who combine these two and build up a whole world around us fooling ourselves to believing a 'nicca' (constant) conceptual world exists.
See, 22.85. Yamaka Sutta; where it discuss the question: 'Is there a re-birth for Arahant after death?'. A monk named Yamaka was in the view that Arahant is not re-born after death. To break this wrong view Maha Sariputta Thero asks Yamaka Thera the following questions:
- Do you think the rupa became Arahant? Yamaka Thera answers: no.
- Do you think vedana became Arahant? Yamaka Thera answers: no.
- Do you think sanna became Arahant? Yamaka Thera answers: no.
- Do you think sankhara became Arahant? Yamaka Thera answers: no.
- Do you think vinnana became Arahant? Yamaka Thera answers: no.
- Was there an Arahant without the above 5 elements? Yamaka Thera answers: no.
- Do you think those 5 elements was the Arahant? Yamaka Thera answers: no.
- Then what Arahant won't be born after death?
While we view that an Arahant will not be re-born after death in the conceptual world, we must realize that the aforementioned process cannot be recognized as a person or animal (satva, puggala saññā) in reality. Just a cause and effect relationship of 5 skhandha which cease to exist when causes of those skhandha ceases (Referred as: skhandha udayabbaya).
Lord Buddha teaches: 'Yadaniccaṁ taṁ dukkhaṁ' - everything that is 'anicca' results 'Dukka'. This does not mean the suffering we feel in our body or mind or loss in material world. The Dukka Ariya Sacca discussed in 4 noble truths must be perceived through wisdom. Its not a thing you can feel. It is not a thing in your mind. It refers to 4 characteristics of elements:
- Pīḷana (Pīḷana atto): This refers to dissolution of cause. If we take the example of the eye; can the photons that bring the picture maintain the picture constantly? No it can't. Can the eye maintain the picture constantly (on its own)? No it can't either. The moment the photons provide the stimulation, the picture was created, and the next moment it ceases to exist. The next moment, a new set of photons provide a new stimulus and eye can generate a new picture which ceases to exist the next moment.
- Saṅkhata (Saṅkhata atto): refers to the elements that are the results of a cause. The picture that resulted due to the stimulus from the photons.
- Viparināma (Viparināma atto): since the causes cannot maintain a constant existence, and they continue to change, the effects have to undergo changes as well. This transforming characteristic is referred to as Viparināma. The photons provided the stimulus ceased to exist in that form, the resulting picture also ceased to exist.
- Santāpa (Santāpa atto): Refers to the maturity of nama and rupa. It is explained that this is related to Tejo dathu which is related to the ability to mature or grow.
Dukka Ariya Sacca is referred to as Dukka due to the above 4 characteristics. Take note that those 4 characteristics exist in everything. Things we evaluate to Happiness, Sadness or upekhā (neither sad nor happy) all things have above 4 characteristics, making Dukka Ariya Sacca a universal truth.