To venture into new territory. The allusion here is to the timid swimmer who is wary of getting into the water at all. Although this particular expression dates only from the early twentieth century, a similar idea was expressed more than four hundred years earlier by John Lyly in Euphues and his England (1580): “I resemble those that hauing once wet their feete, care not hoe deepe they wade”; in other words, once having gotten up one’s nerve to try something new, one is more willing to plunge in all the way. In The Glorious Fault (1960) Leonard Mosley combined two metaphors: “In parliamentary life, he [Curzon] was to be one who stayed to get his feet wet before deciding that a ship was sinking.”