... قُلْ هَلْ يَسْتَوِي الَّذِينَ يَعْلَمُونَ وَالَّذِينَ لَا يَعْلَمُونَ ...

There are two types of people: Those who make material interest their supreme concern; the other make God their supreme concern. It is this second type of individual who is a man of God. His realisation of God is his conscious discovery. He discovers God as the most Majestic and Supreme Being, so much so that all his hopes and all his fears are linked to that one and only Being. His restlessness keeps him out of bed at night. His loneliness is not the loneliness born out of unawareness, but the loneliness of the remembrance of God. A man of knowledge is one whose mind is ignited by the remembrance of God, and that man is devoid of knowledge whose mind is ignited only by material factors. He is awakened only by material shocks and thereafter is lost, deep in slumber.

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (39:9)