there were trees everywhere , thanks to william penn 's dictum that one acre in five should be left in trees-even the avaricious politicians of the twentieth century had n't quite succeeded in deforesting the place , though probably only because they could n't figure out how to make a profit at it without being caught-and many of the trees were in bloom , a confetti of white petals drifting over the horses ' backs as the wagon turned into the city proper .