Anna Laetitia Barbauld - Riddle lyrics

From rosy bowers we issue forth, From east to west, from south to north, Unseen, unfelt, by night, by day, Abroad we take our airy way: We foster love and kindle strife, The bitter and the sweet of life: Piercing and sharp, we wound like steel; Now, smooth as oil, those wounds we heal: Not strings of pearl are valued more, Or gems enchased in golden ore; Yet thousands of us every day, Worthless and vile, are thrown away. Ye wise, secure with bars of bra** The double doors through which we pa**; For, once escaped, back to our cell No human art can us compel.