INTRODUCTION. 



Change is the soul of nature. Stars appear and disap- 

 pear, and new ones come in their stead. The day gives 

 its place to the night, and the night to the day. The 

 moon is ever changing her aspect as she moves round the 

 earth. Spring, summer, autumn, and winter follow each 

 other in succession, and with this gradual change of the 

 seasons, the earth is continually changing its plant-cover- 

 ing. Nature is ever moving onward, and mutability 

 marks all these forward movements. The vegetable 

 world is ever adapting itself to the ever-varying condi- 

 tions of moisture, heat, and light, which mark the days 

 and years of the earth's pilgrimage. One flower, for ex- 

 ample, is seen to open as soon as the first rays of morning 

 tremble on the horizon, another in the morning sun, a 

 third at mid-day, a fourth in the evening, and a fifth at 

 midnight. The animal world, too, strikes as it were the 

 hours. Scarcely do the dew-drops glitter in the beams of 

 the advancing sun, than the earth-worms come to the 

 surface to enjoy themselves, the birds commence their 

 song, the sun rises higher and the woods reverberate with 

 their ever-varied melodies. But the sun sinks in the west 

 and night hides from our view the glory and beauty of 

 nature ; and the nightingale warbles, the owl screams, the 

 bat flies abroad, and an innumerable variety of beautiful 

 moths sport themselves in the gloom. So appear and dis- 



