Beginnings are apt to be shadowy, and so it is with the beginnings of that great mother of life, the sea. Many people have debated how and when the earth got its ocean, and it is not surprising that their explanations do not always agree. For the plain and inesapable truth is that none was there to see, and in the absence of eyewitness accounts there is bound to be a certain amount of disagreement. So  if I tell there is a story of how the young planet Earth aquired an ocean., it must be a story pieced together from many sources and containing many whole chapters the details of which we can only imagine. The story is founded on ihe testimony of the earth's most ancient rocks which were young when the earth was young; on other evidence written on the face of the earth's satellite, the moon; and on hints contained in the history of the sun and whole universe of star-filled space. For although no man was there to witness this cosmic birth, the stars and the moon and the rocks were there, and, indeed, had much to do with the fact that there is an ocean.