They are like trees which have been frequently transplanted.

The earth about them is loose, and they have no roots reaching far into the soil.

They 'light upon every flower,' following their own wayward wills, or because the wind blows them.

They catch opinions, as diseases are caught--when they are in the air.

Borne hither and thither, 'they speedily fall into beliefs' the opposite of those in which they were brought up.