The central message of the poem "Life" by Charlotte Brontë is optimism. Brontë talks about the transience of negative situations, advocating for a "This too shall pass" attitude towards them.
She says that life is not "So dark as sages say." Like most poets, she uses rain to symbolize the troubles of life, but she says that the rain often "Foretells a pleasant day" and causes flowers to bloom, so there is no reason to "lament its fall." In other words, bad things happen for a reason, and for every cloud, there is a silver lining.
She says that even if death takes away our loved ones, and sorrow "seems to win, / O'er hope," hope—personified here as an angel or other celestial being with wings—will always return, bouncing back like elastic.
Finally, she urges us to bear our troubles as stalwartly as we can, for "victoriously, / Can courage quell despair."