Throughout the first six stanzas of the poem, the speaker expresses his genuine sympathy for the plight of the mouse whose home has been destroyed by humans. Indeed, the speaker seems distraught when he proclaims, "Thy wee-bit housie, too, in ruin!" The speaker is particularly sorry that the mouse has no home because "weary Winter comin' fast." The implication is that the speaker worries for the mouse because it will soon be very cold, and the mouse will no longer have the warmth of its house to protect it from the cold.
In the final two stanzas the speaker tries to console the mouse by saying, "The best laid schemes o' Mice an' Men / Gang aft agley." In other words, the best, most thoroughly considered plans of both mice and men often go wrong. Perhaps here the speaker hopes that the mouse might be able to take some consolation in knowing that he is not alone in his misfortune. The implication is that the world can be a cruel place to all creature, and the world is indifferent as to whether those creatures are men, mice, or anything between.
The speaker also says, in the final stanza, that although both men and mice are victims of the cruel and indiscriminate indifference of the world, men are the more unfortunate because men, unlike mice, think back upon the past and forward to the future. The speaker says to the mouse: "The present only toucheth thee." In other words the mouse is fortunate because its present is not made worse by the memory of a better past, or the anticipation of a worse future. The mouse lives only in the present, and so is only touched once by its misfortune. Men, the speaker says, live in the past, the present, and the future, all at the same time, and are touched at once in three different ways by their misfortune.