Memorial Day signals a clear turning point in the Island year. The long weekend carries two messages, one official, the other unofficial. It offers a time to remember and honor those fallen in battle and a moment to celebrate the gathering of summer, even if another month of uncertain New England spring remains. Now comes the season of arrival. The holiday weekend begins for many the journey back to the Island after a long winter’s absence. This is the start of the rush toward summer, that most robust of all Island seasons, when seasonal residents and friends and so many strangers on a first visit to the Vineyard return to this land in the sea.