Meletis Astronomer

[Almosteric]

So  {Meletis Astronomer} says I MAY reveal an enchantment. If I don't do I still have to put those three cards on the bottom of my library? Or just back the way the came off top? 

[Double-O-Scotch]

The remaing cards still go on the bottom. It just gives you a chance to put an enchantment from among them into your hand. Regardless of whether you choose to do so or not, the cards go on the bottom afterwards.