Reordering of sentences (weakness and strength): arrange P, Q, R and S to form a coherent paragraph between S1 and S6. S1: The weak have no place here, in this life or in any other life. Weakness leads to slavery. S6: This is the great fact: strength is life, weakness is death. Strength is felicity, life eternal, immortal; weakness is constant strain and misery; weakness is death.

Introduction / Context:
This passage is a philosophical reflection on weakness and strength. The task is to arrange jumbled sentences P, Q, R and S into a coherent paragraph between S1 and S6. To do this, you must follow the development of the argument from a general statement about weakness to specific explanations involving microbes and mental strength.

Given Data / Assumptions:

• S1: The weak have no place here, in this life or in any other life. Weakness leads to slavery.
• S6: This is the great fact: strength is life, weakness is death. Strength is felicity, life eternal, immortal; weakness is constant strain and misery; weakness is death.
• P: They dare not approach us, they have no power to get a hold on us, until the mind is weakened.
• Q: Weakness leads to all kinds of misery, physical and mental. Weakness is death.
• R: But they cannot harm us unless we become weak, until the body is ready and predisposed to receive them.
• S: There are hundreds of thousands of microbes surrounding us.

Concept / Approach:
We need to build the argument in two stages:

• First, extend the general statement about weakness into a fuller explanation of its consequences.
• Then introduce a concrete example with microbes, showing that they can only harm a weakened person, linking back to the theme that weakness leads to suffering and death.

The sentence describing \"hundreds of thousands of microbes\" must follow a reference that prepares for an example, and the pronoun \"they\" in P and R must clearly refer to the microbes introduced in S.

Step-by-Step Solution:
Step 1: S1 says weakness leads to slavery. Q naturally follows by expanding this idea: \"Weakness leads to all kinds of misery, physical and mental. Weakness is death.\" It deepens the statement from S1. Step 2: Once the general consequences are described, the passage moves to a concrete example. R talks about a unnamed \"they\" that cannot harm us unless we are weak. S identifies \"they\" as microbes surrounding us, so S must come after R. Step 3: P then continues the same example, stressing that these microbes \"dare not approach us\" until the mind is weakened. It still refers to the same \"they\" introduced and clarified earlier. Step 4: Putting this together, we get the order Q → R → S → P between S1 and S6. Step 5: This sequence maintains thematic unity: from overall consequences of weakness, to microbe example, to a concluding summary in S6 about strength and weakness.

Verification / Alternative check:
If you begin with S immediately after S1, the sudden mention of microbes feels abrupt without the bridge provided by Q. Also, any sequence where S precedes R or P but Q appears later breaks the logical flow from abstract consequences to specific illustration. The order Q R S P ensures that pronouns like \"they\" always have a clear noun (microbes) available beforehand or very soon after, keeping the reasoning easy to follow.

Why Other Options Are Wrong:
Option \"P Q R S\": Starting with P leaves \"they\" without an antecedent, and S, which introduces microbes, comes too late to clarify the earlier pronoun references. Option \"P R Q S\": Both P and R talk about \"they\" before S introduces the microbes, causing confusion. Q, which should come early to develop the theme of weakness, is pushed too far down the paragraph. Option \"Q S R P\": Here S introduces microbes too early, before R explains their inability to harm us unless we are weak. The flow of example and explanation becomes weaker and less persuasive.

Common Pitfalls:
A common trap in such questions is to focus only on the order of sentences mentioning the same topic (like microbes) and ignore the abstract sentences that prepare the ground. Always ensure that the passage first states and elaborates a general claim, then supports it with a concrete example, and finally returns to a summarising remark as S6 does here.

Final Answer:
The correct sequence of the middle sentences is Q R S P, giving a clear and logically developed paragraph about weakness and strength.