Mmmm... Rotten Berries!

Usually, when we think of imagery, we're tempted to think only of images-visual images. Man! It goes so much deeper than that! Our sense of sight is only the tip of the iceberg. In addition to it, there are a bouquet of lovely, er...senses, such as taste, smell, audio, touch/feel...
In lit and poetry, I, based on my experience usually don't see all of these clumped together so closely, but it makes sense to do so, as we often experience multiple senses simultaneously. So,
Ladies and gentlemen, gentlemen and ladies, friends, Romans, countrymen-
In Seamus Heaney's "Berry Picking", he manipulates imagery in order to emphasize the change in tone and mood between the first, more fresh and joyous stanza and the following, which evokes frustration and disappointment.

Man- this poem seems as if its entirely comprised of imagery-which is excellent for the establishment of the tone and mood because of the strong appeal to the senses,. In appealing to said human characteristics, Heaney is doing a couple of things. First of all, he's appealing to a huge crowd-the majority of us humans are strongly affectedby the images ( of all types) that we are physically experiencing or reading in black or blue ink. Second of all, he's appealing to one of the things that make us inherently human-to be affected at an emotional level through word, sense, and image. In this case, "You ate the first one and its flesh was sweet/Like thickened wine" Whoa. Take a step back. Obviously, ther's the strong presence of visual imagery and the sense of taste, as well as the simile comparing the ripened fruit to thickened wine-but what does all of this stuff do?The simile has a strong impact-when wine is thickened, it essentially means that it has not been diluted by water- its alcoholic effect is extremely strong. By comparing the fruit to thich, sweet wine, Heaney is suggesting that the fruitis not only pure and euphorically
sweet, but he's also hinting at the effect of the fruit-Like alcohol, the sweetness ogf the berrry
turns into an addiction-it causes the speaker to become drunk with joy and escitement of harvesting more berries. In my opinion, this line does a pretty good job of characterizing the first stanza- with its tone and mood having strong connotations of excitement and joy.

Just as the imagery is capable of bringing such joy in the first stanza, it quickly stomps on it in the second. Note: the imagery emphasizes the change in mood and tone because "when the bath was filled we found fur/A rat-grey fungus, glutting on our cache./The juice was stinking too."
You know-the "rat-grey' description (visualimagery) stood out at me-seeing as it really has a strong impact emphasizing the frustrated tone of this stanza. Seeing as rats are pests crawling with disease, the useof the rat-like description seems fitting-It emphasizes the frustration of this stanza by saying that this fungus, this decay which spoils what we worked so hard to get-is a pest destroying both joy and excitement.