Reflection is a vital step in becoming aware of what is going on around us and of drawing conclusions from it. It is a golden key to open the door of experience, a seedbed where the trees of truth are planted, and the opening of pupil of the heart's eye. Due to this, the greatest representative of humanity, the foremost in reflection and all other virtues, upon him be peace and blessings, states: No act of worship is as meritorious as reflection. So reflect on the God's bounties and the works of His Power, but do not try to reflect on His Essence, for you will never be able to do that.  By these words, in addition to pointing out the merit of reflection, the glory of mankind, upon him be peace and blessings, determines the limits of reflection and reminds us of our limits.
In order to draw attention to the same point, the writer of Al-Minhaj (The Way Traced) writes:
Reflection on bounties is a condition of following this way, While reflection on the Divine Essence is a manifest sin. It is both false and useless to doubt and think about Him, And also means seeking to obtain something already obtained.
The verse: They reflect on the creation of the heavens and Earth (3:190) presents the book of the universe with its way of creation, the peculiarities of its letters and words, the harmony and coherence of its sentences, and its firmness as a whole. By drawing our attention to the universe and calling us to reflect upon it, the Qur'an shows us one of the most beneficial methods of reflection: to reflect on and study the Qur'an, and to follow it in all our thoughts and actions; to discover the Divine mysteries in the book of the universe and, through every new discovery that deepens and unfolds the true believer, to live a life full of spiritual pleasure along a way of light extending from belief to knowledge of God and therefrom to love of God; and then to progress to the Hereafter and God's pleasure and approval this is the way to become a perfect, universal human being.
One can use reflection in every scientific field. However, the rational and experimental sciences are only a first step or a means to reach the final target of reflection, which is knowledge of God, provided that one's mind has not been filled with wrong conceptions and premises. Studying existence as if it were a book to be reflected upon can engender the desired results and provide ceaseless information and inspiration, but only if one admits that all things and their attributes are created by God. This is what is sought and should be done by those who attribute all things to God, and who have attained spiritual contentment through the knowledge, love, and remembrance of God.
Reflection must be based on and start with belief in God as the Originator of creation. If not, one might reach God at some stage of the journey, but will not progress beyond the conviction of God's Existence and Unity. Reflection based on and starting with belief in God as the Creator and unique Administrator of all creation enables continuous progression and increased depths, for new discoveries develop into further dimensions (love of God, "annihilation in and subsistence with God," discovering Divine realities behind things and events). In other words, reflection starting with awareness of God having the Names of "the First" and "the Outer" and progressing toward Him as "the Last" and "the Inner," will enable one to progress uninterruptedly and without end. Encouraging people to engage in reflection focused upon a determined aim entails urging them to learn and use the methods of sciences that study how existence is manifested.
Since everything in the heavens and Earth are the property and kingdom of God, studying every incident, item, and quality also means studying how the exalted Creator deals with existence. The believer who studies and accurately comprehends this book of existence, and then designs his or her life accordingly, will follow the way of guidance and righteousness all the way to the final station of Paradise, where he or she will drink of kawthar the blessed water of Paradise.
The people of loss and perdition wander in the pits of heedlessness and ingratitude to God, the true Owner of the infinite variety of beauty and bounty in the world; those following the way to Paradise, and equipped with reflection, recognize the True Giver of all bounty and obey Him, fully conscious of what believing in Him means. They travel from gratitude to being provided with all bounties, and from bounty to gratitude, in the footsteps of the angels, Prophets, and truthful and loyal believers, and seek God's pleasure in order to thank Him for His blessings. Using the vehicle of reflection and with the help of remembering God, they surmount all obstacles and, progressing from taking necessary measures (to attain their goal), to submission, and from submission to committing their affairs to the Power of God, they fly through the heavens to their final destinations. 
 There are numerous final destinations. Some of them are entering Paradise, obtaining God's pleasure, and being rewarded with His vision.