LIFE IN THE PAST 155 
volving nebulz had come into comparatively close 
proximity to a passing body. The visitor, by its at- 
traction, drew from the nebula a wisp of gas. The 
revolving motion of the nebula gave to the attracted 
arm the spiral form. 
These twisted arms are not equally dense through- 
out, but have thickened knots here and there in their 
course. The Planetesimal Theory suggests that these 
thickened knots are embryo planets and the central 
portion of the nebulz an embryo sun. After all the 
material in such a body has condensed either around 
the knots or about the central mass a new solar sys- 
tem will be complete. As before stated, neither of 
these theories can be said to be demonstrated. Each 
of them has points in its favor and each has its diffi- 
culties. It is pleasant to know what men have clearly 
thought concerning such questions, but for a man not 
a trained geologist neither will carry much convic- 
tion. He will still rest with his own early conclusion 
that whichever shall prove to be true, for him his 
old formula is still valid, “in the beginning God made 
the heavens and the earth.” He will no longer think 
of God as having shaped the balls with his own hand 
and thrown them into space; he will no longer dream 
that it all occurred within a week not more than six 
thousand years ago; but still to him will come the 
reverent conviction that, whatever the plan by which 
