We dearly love our bodies of flesh and blood, but imagine how they would seem to a person whose body had already changed to light. Sort of a slimy prison. A dangerous place to be stuck in.

Incidentally, you maintain the general outer form of a human being when your body does change. Other people (remember the pen and the dog) might even see you the same as before. You and others like you, though, see you as the most exquisite being you can imagine right now, magnified a thousand times over.

And so sometimes the body of light is called the “rainbow” body, because from a distance a rainbow looks like solid stuff, but up close you can pass your hand through it: no more guts and blood.

Since a dog in the end is only the seeds to see things as a dog, a person again who really understands seeds could take on various outer forms, and appear to be born as various different people, if this would help us. He knows it's easier for us, on a day-to-day level, to relate to someone fairly much like ourselves. And so at the beginning he comes to us that way.