The Tillek is the title Speaker of Dolphins, chosen of all the pods for her wisdom. The name given the pod leader was traditional. After the Second Crossing Speaker of Dolphins took on the title in honor of Jim Tillek.
He taught, as had other dolphin instructors, why dolphins had followed humans to this world, far from the waters of Earth, where they had evolved: the chance to inhabit clean waters of an unpolluted world and live as dolphins had before technology had spoiled the Old Oceans of humankind. He knew, and taught this despite the astonishment it caused, that dolphins had once walked on land.
There were some matters taught by the Tillek that had to be learned simply because they mattered as details to the whole story. They must take this on faith for she had had to learn these facts from the Tillek who had taught her. This was fact as well as faith and must be believed, though never experienced. It was History.
Tillek said - the dolphins would keep to their patrols of the coastline, and when, if ever, a human listened to them, at least they could tell him what had changed, and save his ship from being broken on unexpected reefs or rocks; or warn him of where the Currents had altered and might be a hazard to the ships and the humans who sailed on them.