Those men who can rid their veins of warmth and who do not let compassion affect them before they die are happy. The front line breaks, and those men are fading troops, not flowers for poets to play with. They are barely men, merely "gaps for filling" and the numbers in the official losses. No one cares about them.
Some of them stop feeling any emotion, for themselves or for others. Dullness is the solution for the incessant shelling. It is easier to rely on chance rather than trying to figure out when the shells might fall. They do not even bother trying to assess the destruction of the armies in the war.
Those who no longer have an imagination are also happier; imagination is too heavy a weight when they have to carry their packs and ammunition around. Old wounds do not ache anymore. They are not even affected by the color of blood, having seen "all things red" in battle. The pulsing of terror is over. Their senses have been ironed and cauterized, and they are able to laugh even among the dying, completely unfeeling.
The soldier at home is happy, as he does not know about the dawn full of attacks. The boy whose mind was never trained is happy as he sings along the march. The march is long and dreary and unceasing, "from larger day to huger night".
Those wise soldiers cannot think how else to view their task. They are not overly necessary while alive, and are not valuable when they are dying. They are not sad or prideful or even curious. The speaker wonders how their attitudes are different from "old men's placidity".
However, these "dullards" are cursed as they stand like stones before cannons. They are wretched and base. It was their choice to make themselves immune to feeling and pity and the part of man that causes him to moan before the stars. They do not care about what mourns when men die, or what "shares / The eternal reciprocity of tears".
Written around April 1918, "Insensibility" is one of Owen's longest poems, and continues one of the major themes in his oeuvre – the psychological mechanisms that soldiers utilize to stomach their horrific situation. It features a broken rhythm and irregular meter. The stanzas are of unequal length, but Owen employs his famous pararhyme consistently throughout the poem.
In the first stanza Owen begins by saying that soldiers are happier when they can desensitize themselves to the war. Compassion is useless, and they certainly should not be looked at as rife with poetry or sentiment. The soldiers are barely men, in fact – just "gaps for filling" and the numbers that make up the losses. No one really cares about them. This belief, beautifully articulated by Owen, that the young soldiers are replaceable and less than human is present in the work of all of the great WWI poets. Of course, Owen's poetry seeks to refute those truths and to give dignity and worth to the young men so brutally ignored; he does "bother" with them.
In the second stanza he continues, saying that the young men do not care about themselves or about others anymore. They have dulled their senses and do not try to make heads or tails of their situation. It is easier to take things as they come, and they barely even pay attention to the course of the war. One of the common themes voiced in the recollections of WWI is just how utterly irrational it all seemed, and "Insensibility" gives voice to that assertion. In the third stanza Owen claims that these soldiers are better off without an imagination; no doubt it is simply too painful to consider life at home, or the possibilities for a normal life after the war. All of these emotions are simply extraneous and unnecessary; there is no point to colors like red, for they have "seen all things red", and they no longer feel anything like fear. Used in "Greater Love" to symbolize romance, here red can only mean blood. In one of the most disturbing images, the soldiers "laugh among the dying, unconcerned". There is no point in wasting one's tears on the dead, as they are too many to count.
In the fourth stanza the soldier who returns home is happy because he does not have to know more about the battles, and the soldier who never learned the value of emotion or feeling in the first place is happy as well. Suddenly, in the middle of this stanza, Owen switches to first person, using "we" to depict him and his fellow soldiers marching along solemnly and interminably. He speaks not of universal truth, but his own specifically as well. The days and nights meld into one long darkness and soldiers have little to alleviate their boredom and despair.
In the fifth stanza, the most complicated thus far, Owen seems to be contrasting people like himself, the "wise", the poets, who are not yet insensible to what is going on, with the soldiers who are not "sad, nor proud, / Nor curious at all". The question seems to be how a poet can be a poet and a soldier. If he becomes insensible to the war, how can he use his voice for a higher purpose? If he stays sensible, how can he psychologically deal with the sheer horror of it all?
In the last stanza Owen shifts his perspective a bit, saying that the insensible "dullards" are cursed and wretched. The happiness that the soldiers-turned-ciphers experience has been purchased at a high price, for they no longer have any understanding of humanity. Owen does not outright condemn these soldiers, understanding why they suppress their feelings as they do, but he feels a profound sadness at this lack of pity.