In reality, Edward was the perilous companion.

He was composed of better stuff.

Algernon was but an airy animal nature, the soul within him being an effervescence lightly let loose.

Edward had a fatally serious spirit, and one of some strength.

What he gave himself up to, he could believe to be correct, in the teeth of an opposing world, until he tired of it, when he sided as heartily with the world against his quondam self.
Algernon might mislead, or point his cousin's passions for a time; yet if they continued their courses together, there was danger that Algernon would degenerate into a reckless subordinate--a minister, a valet, and be tempted unknowingly to do things in earnest, which is nothing less than perdition to this sort of creature.
But the key to young men is the ambition, or, in the place of it, the romantic sentiment nourished by them.