Does the human spirit exist?

Am I right in saying that the Spirit that animates the lower creation is the same in kind as that of man—the differences being accounted for by the organisation into which the Spirit enters?

In man, as I have said frequently, you will find the whole of creation. 

The Spirit of the animal is in a low state of development in accordance with its organisation, and Spirit is the grand animating power down through all forms to the meanest speck that exists. 

But in you, there is an inner Spirit, and your brain becomes the seat of intelligence—the organ through which the grand inner you works. 

You will find a little of your intelligence in this one and that one of the lower creation, but nowhere will you get a brain equal to yours.

In bodily form, you will get nothing better than you.

In other worlds, you may find beings with bodies of finer material—some so fine that they may be said to glide away into Spirit, but still the form is human. 

But it would require hours to do justice to this subject. 

I would need to begin with life in its lowest forms up through the varied grades until we came to the source and workings of intelligence—how the inhabitants of the air, land and waters are affected by the Sun's rays and magnetic currents.