Final answer:
Socrates illustrated the lesson that pleasure and pain often arrive together in life, conveying the inseparable nature of these experiences and the deep philosophical understanding of human existence.
Step-by-step explanation:
When Socrates talked about his leg at the beginning of the passage, the lesson he was trying to impart to his followers was that pleasure and pain often arrive together in life. This philosophical observation emphasizes the dual nature of experiences and the inevitability of facing both positive and negative aspects concurrently. It aligns with Socratic thought on the interconnectedness of life's experiences and the notion that one cannot fully appreciate joy without having known sorrow, essentially choosing answer D) Pleasure and pain almost always arrive together in life.