One of the first discoveries we made in our study of the Moon’s Vegetable Kingdom was that there was practically no warfare going on between it and the Animal Kingdom. In the world we had left we had been accustomed to see the horses and other creatures eating up the grass in great quantities and many further examples of the struggle that continually goes on between the two. Here, on the other hand, the animals (or, more strictly speaking, the insects, for there seemed as yet hardly any traces of other animal species) and the vegetable life seemed for the most part to help one another rather than to fight and destroy. Indeed we found the whole system of Life on the Moon a singularly peaceful business. I will speak of this again later on. We spent three whole days in the investigation of the strange music we had heard. You will remember that the Doctor, with his skill on the flute, was naturally fond of music; and this curious thing we had met with interested him a great deal. After several expeditions we found patches of the jungle where we were able to see and hear the tree music working at its best. There was no doubt about it at all: The trees were making the sounds and they were doing it _deliberately_. In the way that an Æolian harp works when set in the wind at the right angle, the trees moved their branches to meet the wind so that certain notes would be given out. The evening that the Doctor made this discovery of what he called the _Singing Trees_, he told me to mark down in the diary of the expedition as a Red Letter Date. I shall never forget it. We had been following the sound for hours, the Doctor carrying a tuning-fork in his hand, ringing it every once in a while to make sure of the notes we heard around us. Suddenly we came upon a little clearing about which great giants of the forest stood in a circle. It was for all the world like an orchestra. Spellbound, we stood and gazed up at them, as first one and then another would turn a branch to the steady blowing wind and a note would boom out upon the night, clear and sweet. Then a group, three or four trees around the glade, would swing a limb and a chord would strike the air, and go murmuring through the jungle. Fantastic and crazy as it sounds, no one could have any doubt who heard and watched that these trees were actually making sounds, which they _wanted to make_, with the aid of the wind.