The Quran

وَما يَستَوِي البَحرانِ هٰذا عَذبٌ فُراتٌ سائِغٌ شَرابُهُ وَهٰذا مِلحٌ أُجاجٌ ۖ وَمِن كُلٍّ تَأكُلونَ لَحمًا طَرِيًّا وَتَستَخرِجونَ حِليَةً تَلبَسونَها ۖ وَتَرَى الفُلكَ فيهِ مَواخِرَ لِتَبتَغوا مِن فَضلِهِ وَلَعَلَّكُم تَشكُرونَ

Ali Unal

Nor are the two seas (large bodies of water) alike: this one is sweet and palatable, and pleasant to drink, but that one, salty and bitter. You obtain from both fresh meat (for your nourishment), and precious stones to wear as ornament. And you see ships plowing through (both kinds of water), so that you may seek of His bounty, and that you may give Him thanks.¹

The Qur’ān draws our attention to the two types of seas (and similar large bodies of water) in some other verses (e.g., 25: 53). The material origin of the universe is one single matter, namely ether (see sūrah 2: 29, note 8; sūrah 11, note 2); and all things in the universe are made of basically four substances: hydrogen, oxygen, carbon, and nitrogen. Despite the simplicity of origin, there is almost an infinite variety of creatures in the universe. Moreover, all human beings are created, originally, from earth. The biological origin of every human being – male sperm and female ovum – is also made of the same substances, and all parents are nourished with the same. But there is a world of difference between human beings in many aspects. This infinite variety in apparent similarity clearly demonstrates God and His absolute freedom, and based on many instances of wisdom.