Love's Presence: The sonnet begins by describing the speaker's love as a "lively spark" that can endure trials and sorrows. Despite all the struggles, love remains persistent and steady, like a flickering candle resisting the darkness.
Life's Fragility: The speaker compares the brevity of human existence to a fragile blossom that blossoms and withers away in a short span. He laments the fleeting nature of life and the constant fear of death. The speaker draws parallels between the transience of flowers and the fragility of emotions and relationships.
Love as a Remedy: In contrast to life's instability, the speaker holds onto love as an enduring, life-affirming force. Love, unlike a flower that fades with time, can conquer death and defy decay. The speaker believes love can provide solace, strength, and comfort amidst the uncertainties of life.
Eternal Love: The final couplet expresses the speaker's conviction that his love for the beloved is timeless. It will transcend the boundaries of death and persist beyond mortal life. The speaker confidently asserts that their love is "eternal and immortal."
Overall, Sonnet 43 deals with the enduring nature of love amidst the transient nature of human life. It's a contemplation of love's ability to provide stability, hope, and immortality in a world marked by uncertainty and brevity.