"And with Him are the keys of the Unseen.
"And with Him are the keys of the Unseen. None but He knows them. And He knows whatever is in the land and the sea; and no leaf (of a tree) drops down but He knows it, nor is there a grain in the darkness of the earth nor anything wet or dry but it is (noted) in a clear Book." Secrets of the Unseen! In the former verses, the words were about Allah’s Knowledge, Power, and the expansion of the circle of His commandment.
From this verse on, the meaning stated in those verses concisely has been mentioned with some explanation. At first, the subject of Allah’s knowledge is pointed out. The verse say's "And with Him are the keys of the Unseen. None but He knows them. ..." Then, for a more emphasis and explanation, it adds: "... And He knows whatever is in the land and the sea....." The Arabic term /barr/ means 'a vast place', which is usually used for a (dry) land.
The term /bahr/ originally also means 'a vast place' where a plenty of water is found. It is often applied for the seas and, sometimes, for the great streams. However, Allah’s knowledge upon whatever exists in the lands and the seas is something which hints to Allah’s omniscience, and that His knowledge encompasses all things. That is, He knows the movements of millions of million living creatures, small and big, in the depths of the seas.
He knows the true number of the cells of every human being as well as his blood cells. He knows the mystic circulations of all electrons inside atoms. And, finally, He knows all thoughts and contemplations pass through different parts and levels of our minds and those which penetrate into the depths of our soul. Yes, He knows equally all of these things! Again, in the second phrase, in order to emphasize on Allah’s Omniscience, it has particularly pointed to this aspect, and says: "...
and no leaf (of a tree) drops down but He knows it, nor a grain in the darkness of the earth ..." In fact, it has taken two sensitive subjects with which no human being can be thoroughly acquainted even if he lives millions of years and that the technical sets be surprisingly completed. Who knows that, in each day, which seeds the winds separate from the plants throughout the earth, and on which spots of the ground they scatter them?
Which electronic mind can count exactly the number of the leaves that separate from the branches of trees of the forests only during a day?