What does the simile "I got that sunshine in my pocket" mean?

Read this sentence from the story of my life by helen keller. the most important day i remember in all my life is the one on which my teacher, anne mansfield sullivan, came to me. which element of plot does this sentence best represent?

Time is not always change. time can also mean continuity, and it can mean keeping acknowledged truths in mind despite differences in circumstances.there is no better example of this in things fall apart than the retellings of the proverb about the bird named eneke, the language in both retellings is almost identical despite the length of time that has passed between their repetitions. in comparing the usages of the same proverb, achebe allows his readers to note the similarities and differences between the situations, and he them understand how this story can be applied to their own lives.

How are correlation and causation similar?