Understanding the Passage and the Blank

The passage discusses two distinct functions of the human mind, focusing on the "active function" which involves volitional, voluntary thinking. The sentence we need to complete is: "This function is used __________the active, wide-awake man in his busy and energetic moments."

We need to choose the word that correctly links the "function" to the "active, wide-awake man," indicating who uses the function.

Analyzing the Options for the Blank

Let's examine each provided option to see which one fits grammatically and contextually into the blank space:

• By: If we insert "By", the sentence becomes "This function is used By the active, wide-awake man...". This structure correctly identifies the "active, wide-awake man" as the agent performing the action (using the function). This is a standard passive voice construction where the agent is introduced by "by".
• with: If we insert "with", the sentence becomes "This function is used with the active, wide-awake man...". This implies the function is used alongside the man, or perhaps that the man is an instrument with which the function is used, neither of which fits the intended meaning of the man being the one who utilizes the function.
• plus: If we insert "plus", the sentence becomes "This function is used plus the active, wide-awake man...". "Plus" is used for addition. This is grammatically incorrect and makes no sense in this context.
• around: If we insert "around", the sentence becomes "This function is used around the active, wide-awake man...". "Around" typically indicates location or proximity. It does not convey that the man is the user of the function.

Determining the Correct Preposition

Based on the analysis, the preposition "By" is the only option that correctly indicates that the "active, wide-awake man" is the person who uses "This function". The phrase "used by someone" is a common way to express the agent in a passive sentence.

Explanation of the Correct Answer

The correct answer is 'By' because it correctly completes the passive sentence structure. The sentence states that "This function" (the active function of the mind) is utilized. We need to specify who utilizes it. The phrase "used by the active, wide-awake man" clearly states that the man is the one doing the using.

Therefore, in the sentence "This function is used __________the active, wide-awake man...", 'By' is needed to identify the agent using the function.

Revision Table: Passage Blanks Context

To understand the flow of the passage, let's look at the likely completed blanks based on common English usage and the context provided (solving all blanks isn't required for this specific question, but it aids understanding):

Filling in the fifth blank with 'By' aligns perfectly with the passive construction indicating who uses the function.

Additional Information: Active Mentation

The passage introduces the concept of "Active Mentation" as the conscious, voluntary control and focusing of the mind. This contrasts with perhaps a more passive or wandering state of thought. Key aspects mentioned include:

• It is a deliberate process.
• It involves focusing the mind on a specific problem.
• It requires excluding irrelevant thoughts.
• It is associated with individuals who are active, alert, and engaged in their work.

Understanding Active Mentation helps clarify why such a function would be described as being "used by the active, wide-awake man" - because this state of mind is characteristic of someone deliberately engaged in focused thinking.