Option A is correct. Nature ordains that the human race shall perish of famine if it stops working." This directly implies that work is essential for human survival. The inability to work leads to the end of the human race, highlighting the necessity of work as a fundamental part of life. Therefore, the passage suggests that work is not optional but a natural requirement for survival.

Option B is incorrect. While the passage mentions, "The question we have to settle is how much leisure we can afford to allow ourselves," this idea is secondary to the main point of the necessity of work. The passage is primarily focused on the obligation to work, while the balance between work and leisure is presented as a secondary consideration.

Option C is incorrect. The passage refers to work as a "tyranny," but this term is used in the context of work being an unavoidable and necessary aspect of life. It is not portrayed as a negative force in itself, but rather as something that humans must accept for survival. Thus, while work is called a tyranny, it is not the central theme of the passage.

Option D is incorrect. The passage does not focus on understanding the nature of work. It stresses the obligation to work for survival and mentions leisure in passing, but it does not emphasize the need for an intellectual or philosophical understanding of work. Therefore, this statement is not directly supported by the passage.