In short, from the time a bird bursts its shell until it dies, save intervals of sleep, it is never still for a moment. From these considerations it may reasonably be affirmed that whereas the normal state of animals, including even man, is quietude, that of birds is motion. We find also that birds are so endowed that their natural qualities harmonise with the exterior qualities and conditions of their life; this again makes them better adapted for happiness than other animals. They have remarkably acute powers of hearing, and a faculty of vision almost inconceivably perfect. Owing to this last they can discern simultaneously a vast extent of country, and are daily charmed by spectacles the most immense and varied. From these things it may be inferred that birds ought to possess an imagination, vivid and powerful in the highest degree,. Not the ardent and stormy imagination of Dante or Tasso; for this is a disastrous endowment, and the cause of endless anxieties and sufferings. But a fertile, light, and childish fancy, such as is productive of joyful thoughts, sweet unrealities, and manifold pleasures. This is the noblest gift of Nature to living creatures. And birds have this faculty in a great measure for their own delight and benefit, without experiencing any of its hurtful and painful consequences. For their prolific imagination, as with children, combines, with their bodily vigour, to render them happy and contented, instead of being injurious, and productive of misery, as with most men. Thus, birds may be said to resemble children equally in their vivacity and restlessness, and the other attributes of their nature. If the advantages of childhood were common to other ages, and its evils not exceeded later in life, man might perhaps be better able to bear patiently the burden of existence. To me it seems that the nature of birds, considered aright, is manifestly more perfect than that of other animals. For, in the first place, birds are superior to other animals in sight and hearing, which are the principal senses of life. In the second place, birds naturally prefer motion to rest, whereas other creatures have the contrary preference. And since activity is a more living thing than repose, birds may be said to have more life than other animals. It follows therefore that birds are physically, and in the exercise of their faculties, superior to other creatures. Now, if life be better than its contrary, the fuller and more perfect the life, as with birds, the greater is the superiority of creatures possessing it, over less endowed animals. We must not forget also that birds are adapted to bear great atmospheric changes. Often they rise instantaneously from the ground far up into the air, where the cold is extreme; and others in their travels fly through many different climates.