And then there is the poet Kenneth Koch, who while travelling in Kenya came to a railroad crossing at which this sign was posted: One train may hide another. This was meant, of course, as a warning to drivers of the fact that the train you see may not be the only train to reckon with, but it also meant, as Koch points out in his poem, that there are many things in this life that conceal other things. One letter may mean another is on the way; one hitch-hiker may deliberately hide another one by the side of the road; offer to carry one bag and you may find there is another one hidden behind it, with the result that you must carry two. And so on through life. Do not count on things coming in ones.