The Quran

وَلَوِ اتَّبَعَ الحَقُّ أَهواءَهُم لَفَسَدَتِ السَّماواتُ وَالأَرضُ وَمَن فيهِنَّ ۚ بَل أَتَيناهُم بِذِكرِهِم فَهُم عَن ذِكرِهِم مُعرِضونَ

Muhammad Asad

But if the truth¹ were in accord with their own likes and dislikes, the heavens and the earth would surely have fallen into ruin, and all that lives in them [would long ago have perished]!² Nay, [in this divine writ] We have conveyed unto them all that they ought to bear in mind:³ and from this their reminder they [heedlessly] turn away!

I.e., the reality of all creation.
I.e., if the universe - and, especially, human life had been as devoid of meaning and purpose as they imagine, nothing could have endured, and everything would have long since perished in chaos.
For this rendering of the term dhikr; see note 13 on 21:10.