Among other things, the speaker in "Naming of Parts" is an excellent example of an introvert in literature. According to C. G. Jung, who coined the terms "introvert" and "extravert" in his book Psychological Types:
The introvert sees everything that is in any way valuable to him in the subject; the extravert sees it in the object.
In other words, the introvert is interested in what the object means or suggests to him rather than in the object itself. For an extreme introvert this is always true. In this case the object is a rifle being demonstrated to a group of new recruits. The poem is based largely on what thoughts and feelings the speaker derives from the elementary lecture given by some noncommissioned officer. For example:
This is the safety-catch, which is always released
With an easy flick of the thumb. And please do not let me
See anyone using his finger. You can do it quite easy
If you have any strength in your thumb. The blossoms
Are fragile and motionless, never letting anyone see
Any of them using their finger.
And this you can see is the bolt. The purpose of this
Is to open the breech, as you see. We can slide it
Rapidly backwards and forwards: we call this
Easing the spring. And rapidly backwards and forwards
The early bees are assaulting and tumbling the flowers:
They call it easing the Spring.
Everything about the gun suggests completely inappropriate thoughts. We can well understand why the speaker, presumably the poet Henry Reed himself, is so unhappy in this situation. He is an intellectual and an introvert caught up as a wartime draftee in a mindless and extroverted military machine. His period of service will be an unhappy one, if he manages to live through it.