Evolving Levels of Thought

Gradually, at various points in our childhoods, we discover different forms of conviction. There’s the rock-hard certainty of personal experience (“I put my finger in the fire and it hurt,”), which is probably the earliest kind we learn. Then there’s the logically convincing, which we probably come to first through maths, in the context of Pythagoras’s theorem or something similar, and which, if we first encounter it at exactly the right moment, bursts on our minds like sunrise with...

 The Earth is Not the Center of the Universe

To a body of infinite size there can be ascribed neither center nor boundary ... Just as we regard ourselves as at the center of that universally equidistant circle, which is the great horizon and the limit of our own encircling ethereal region, so doubtless the inhabitants of the moon believe themselves to be at the center (of a great horizon) that embraces this earth, the sun, and the stars, and is the boundary of the radii of their own horizon. Thus the earth no more than any other world i...

 Animals Evolved onto the Land and Took the Ocean With them

If you go back far enough, everything lived in the sea - watery, salty alma mater of all life. At various points in evolutionary history, enterprising individuals from many different animal groups moved out on to the land, sometimes eventually to the most parched deserts, taking their own private sea water with them in blood and cellular fluids. In addition to the reptiles, birds, mammals and insects we see all around us, other groups that have succeeded in making the great trek out of life's...