The verse 185 has invited mankind to practice two important things. Firstly, to make thoughtful observation of the creation of Allah, the heavens, the earth and the things existing between them. Secondly, to be mindful of the period of life given to an individual. It does not require to be a genius to perceive the signs of Allah's power and wisdom in everything around us. A little amount of serious thought is enough to make one see that everything, rather every particle of this world, is singing the praise of it's Creator and is, in itself, a strong proof of Allah's power and wisdom. Any one applying his intellect in conscious observation of things cannot avoid natural demand of faith in Allah, the One.
Being mindful of uncertain period of one's life makes him more active in attaining his objectives, because he is not sure how much time of life he has at his disposal. It would be noticed that all crimes and evil deeds are activated by disregard to one's death. Those who are conscious of their indefinite period of life mostly avoid involving themselves in unwanted activities. The Holy Prophet ﷺ said:
اَکثرُوا ذکرَھَا ذِم اللَّذَّاتِ المؤت
"Frequently remember the thing which eliminates the pleasures - the death."
The verse 185, has therefore said:
"Have they not looked into the kingdoms of the heavens and the earth, and into things Allah has created, and into the fact that their time may possibly have drawn near."
The Arabic word مَلَکُوت (Malakut) signifies kingdom indicating a superlative degree, that is, the great Kingdom. The verse implies that the disbelievers have not used their common intellect in seeking the Truth which is evident in everything created by Allah, nor are they mindful of the uncertainty of life which may come to an end any moment, depriving them of all the chances of accepting the truth and repenting to Allah for their evil deeds. The last sentence of the verse warned them saying:
"In what other word, then, shall they believe after it?" That is Allah has provided them with transparent signs, both internal and external, of the right path and of the True Faith. Those who are neglectful of such clear signs, there is nothing in the world to guide them to the right path.