One of the principles of the Holy Quran is an invitation for thinking and pondering: pondering over the creation of God so as to follow the secrets of its creation, thinking about our conditions and deeds for doing our duty, contemplating in the history and life of earlier people so as to understand the Divine laws and commandments for the socials life of mankind.
In other words, in the schedule of Islam, so that the nature and intelligence of man may awake, an emphatic order has been given for thinking and contemplating. Islam has given much importance to this. Here we suffice to quote some verses and some narrations:
Verses
1- Do they not reflect within themselves: Allah did not create the heavens and the earth and what is between them two but with truth, and for an appointed term? And most surely most of the people are unbelievers of the meeting of their Lord.
2- Most surely in the creation of the heavens and the earth and the alternation of the night and the day there are signs for men who understand. Those who remember Allah standing and sitting and lying on their sides and reflect on the creation of the heavens and the earth: Our Lord! Thou has not created this in vain! Glory be to Thee; save us then from the chastisement of the fire.
Traditions
1- Imam Sadiq (a.s.) said:??? worship is pondering constantly about the Lord Almighty Allah and His Power.
2- Muammar says he heard from Imam Reza (a.s.): It is no worship to indulge more and more in praying and fasting Rather it is ponder over Almighty Allah's command.
3- Imam Sadiq (a.s.) has said: Most of the worship of Abu Zar was contemplating and taking admonition therefrom.
4- Again Imam Sadiq (a.s.) says: One hour's contemplation is better than worship of one year. Intelligent people are aware of this.
Some points regarding reason
The subject of reasoning is one of those subjects which have been mooted about the creation of this universe and the creation of man as we have seen in the above quoted ayats . This thing is pointed out in the following verse also: Most surely in the creation of the heavens and the earth and the alternation of the night and the day, and the ships that run in the sea with that which profits men, and the water that Allah sends down from the cloud, then gives life with it to the earth after its death and spreads in it all kinds of animals, and the changing of the winds and the clouds made subservient between the heaven and the earth, there are signs for a people who understand.
The Lord of the Universe has, in this verse, invited attention to some issues
The creation of the skies and the earth. Only in the galaxy which is a part of our solar system and which is considered to be one of the thousand of the galaxies in the outer space there are millions of bright suns and bright stars. Moreover, according to calculations of space experts, in between them there are millions of inhabitative planets with milliards of living things therein.
A- Outcome of the day and the night with a distinct regularity.
B- Regular winds that blow over the surface of oceans perennially thereby making ships move.
C- Order has been given to think over the life-giving and the blessed drops of rain.
D- Reminds the reader of the winds that blow on earth besides oceans.
E- The Quran orders us to ponder over the folded clouds over our head that move constantly and keep hanging against the law of gravity millions of tons of pure water and move in every direction.
Thinking about the Hereafter life after death.
Someone asked Imam Sadiq (a.s.) what is the reality behind saying that one hour of thought is better than one your of worship? He replied: So that man may look at his ruined houses and the abodes they have lost and take admonition from their end.
Man must also think about the powerful men who had oppressed people for a long time and take lesson from their fateful end.
Indeed there have been examples before you; therefore travel in the earth and see what was the end of the rejecters.
And also says the Holy Quran: So those are their houses fallen down because they were unjust, most surely there is a sign in this for a people who know.