The Qur'aan was revealed at a certain time and in reference, in many cases, to a certain people or incident. It is sometimes easy for the reader to become complacent and to think of the Qur'aan in terms of referring just to something that happened, something bygone. He thereby closes his eyes unconsciously to the fact that the Qur'aan was not revealed only for a specific era or for a specific people. Instead it is the guidance for all of mankind until the Day of Judgement. It contains lessons that transcend the constraints of time and place. The reader must open his eyes and realise that the Qur'aan, although it refers to specific events, is laying down lessons and principles that are valid for all times and places.
Instead of thinking only about the event referred to, it is must more important for the reader to think about how the Quranic lesson is being manifested in front of his own eyes or is to be applied in his times.
This is not meant to downplay the importance of the science of asbaab an-nuzool (the study of the events leading up to a specific revelation). In many cases, the actual meaning or proper intent of a particular verse cannot be fully understood without looking to the verse's asbaab an-nuzool. But that does not mean that the verse itself or its ruling or lesson is restricted to only that occasion or only to those individuals to whom it was originally referring. If that were the case, then perhaps much of the Qur'aan would have no validity today. This important point is why scholars agree upon the maxim: the ruling is determined by the generality of the text and not by the particularity of the occasion of the ruling.
That the text of the Qur'aan was not to be confined by time and place was something well known to the scholars of tafseer throughout the ages. Whenever they turned to the Qur'aan, they found guidance for their own place and time because they realised that the lessons and rulings of the Qur'aan were not to be restricted to the time of the Companions رضي الله عنهم of the Prophet صلى الله عليه وسلم. This was clearly reflected in their commentaries of the Qur'aan. Salaahud-Deen Al-Khaalidi notes,
"Each and every generation of Muslims found in the text of the Qur'aan a discussion of what they were passing through and what would improve their lives as if the Qur'aan was being revealed at that moment in particular. Every one of the commentators of the Qur'aan started from the texts of the Qur'aan to develop and train his people and make their situation better. And from every commentary on the Qur'aan one can derive the level of culture and civilisation, customs, social life, level of belief and behaviour for the period in which the commentator lived. That commentary was a recording of the civilisation and history of that period. That was only the case because the texts of the Qur'aan were applicable to the time and place of the commentator and were directed to the people around him." 
When the reader approaches the Qur'aan with this perception in his mind, not thinking that this verse was referring to the disbelieving tribes and so on, but thinking that each and every verse is actually giving a meaning that is relevant to what is happening around him, then he will see the Quranic messages living in front of his own eyes. He will read verses, that were originally revealed in reference to specific people or incidents, and see them being re-enacted around him in his life. Instead of thinking that the verses are talking about something that has passed, he will realise the Qur'aan is referring to living and happening events, things that occur over and over in the history of mankind and that are occurring around him while he is reading the Qur'aan, regardless of whether he be at the Ka'bah, in Karachi or in New York.
For example, Allaah سبحانه و تعالى says in the Qur'aan,
(Soorah Hajj, 22:11)
A look at Imaam at-Tabari's رحمه الله commentary tells us that this verse was revealed concerning some of the bedouin tribes around Madeenah who entered Islaam and stayed with the Prophet صلى الله عليه وسلم only if such a venture turned out good for them. 
Obviously, if when reading this verse, the reader simply thinks in his mind about those bedouin tribes only, he will be missing the real guidance of the Quranic verse. Instead he should look around him and see how until this day such people exist. He should take a warning from this verse and realise that the behaviour described in this verse is not something that was exhibited by some people during the time of the Messenger of Allaah صلى الله عليه وسلم but it is a behaviour that will be repeatedly appearing throughout the history of mankind. If the reader applies the Qur'aan to the life around him, he will see this verse demonstrated in front of him. Even more importantly, because of his alertness, he might find that he himself exhibits this kind of behaviour. He might realise that the verse is actually talking about him. Because he approached the Qur'aan in the correct manner, releasing its text from contraints of time and place, he will be able to notice his grave mistake and correct himself before it is too late.
This is in contrast to the person who reads the Qur'aan thinking that those verses refer to bygone people and misses the relevance of the text to his own time. He does not realise that the Qur'aan is describing what is happening around him or, perhaps, most importantly, what he himself is doing.
In another verse, Allaah سبحانه و تعالى states,
(Soorah Aali 'Imraan, 3:173)
One does not have to turn to any commentary on the Qur'aan to realise that this verse was revealed concerning a specific people at a specific event. This is quite clear from the wording and context of the verse. Yet the lesson it contains is a very important one, especially for Muslims living in times like today when they are very weak and the enemies of Islaam are taking advantage of their economic and military superiority.
What a loss it would be for the reader to read this verse just thinking about it as a historical happening and not realising what an example and lesson it contains for him. In this verse, Allaah سبحانه و تعالى is making it clear that the true believers with a correct understanding of Islaam know that the enemies of Islaam will gather against them. When this occurs, they know that Allaah's سبحانه و تعالى promise and plan for this world is true and this only increases their eemaan (faith) and never increases their fear of the enemies of Allaah سبحانه و تعالى. This was the case of those people concerning which this verse was originally revealed and the reader should realise that this should be his response, since he claims to be a true believer, whenever he comes across a similar situation.
When the Qur'aan is freed from constraints of time and place it really has a living and vital effect on the reader. When he closes the Qur'aan upon the contemplation of his reading, his vision and sight are now at a new level. As he looks around him, as he hears people speak or sees them act, in fact, as he himself speaks or acts, the verses of the Qur'aan flow directly to his mind and he says to himself, "This is exactly what Allaah سبحانه و تعالى was describing. This is exactly what that passage was talking about."
This will make him realise the reality of the Qur'aan as well as the reality of Allaah's سبحانه و تعالى presence, the importance of believing in and submitting to Him, the reward for doing right and the punishment for doing wrong. And, furthermore, when he comes across those aspects of life that the Qur'aan discusses, he will know how to respond in the manner that is pleasing to Allaah سبحانه و تعالى because he knows exactly what Allaah سبحانه و تعالى has said about that aspect in the Qur'aan and how he should behave to attain Allaah's سبحانه و تعالى pleasure. Far different will this person be from the one who reads the Qur'aan and in his mind he is thinking that each verse is referring to something that happened - something past, something gone, something dead - and thereby he makes the Qur'aan something past and dead as if it is not meant for today. The Qur'aan, therefore, does not breathe into him the guidance that it contains - guidance that is relevant and real for every time and place.