Imagine that every man’s mind is an island, surrounded by ocean. Each seems isolated, yet in reality all are linked by the bedrock from which they spring. If the oceans were to vanish, that would be the end of the islands. They would all be part of one continent, but their individuality would have gone. Telepathy, as you have called it, is something like this. In suitable circumstances minds can merge and share each other’s contents, and carry back memories of the experience when they are isolated once more. In its highest form, this power is not subject to the usual limitations of time and space.
(..)
You must face this fact; yours is the last generation of Homo sapiens. In a few years, it will all be over, and the human race will have divided in twain. There is no way back, and no future for the world you know. All the hopes and dreams of your race are ended now. You have given birth to your successors, and it is your tragedy that you will never understand them - will never even be able to communicate with their minds. Indeed, they will not possess minds as you know them. They will be a single entity, as you yourselves are the sums of your myriad cells. You will not think them human, and you will be right. (..) What you have brought into the world may be utterly alien, it may share none of your desires or hopes, it may look upon your greatest achievements as childish toys - yet it is something wonderful, and you will have created it. When our race is forgotten, part of yours will still exist. Do not, therefore, condemn us for what we were compelled to do. And remember this - we shall always envy you.

//Arthur C. Clarke, 1953, Childhood's End