2 adjectives to describe impulsion

History may not be a very practical study, but it teaches some useful lessons, one of which is that nothing is accidental, and that if men move in a given direction, they do so in obedience to an impulsion as automatic as is the impulsion of gravitation.

"Sound, Mr. Spinrobin," he said, with a sudden and effective lowering of his booming voice, "is the original divine impulsion behind naturecommunicated to language.

2 adjectives to describe  impulsion