Symbolism, Imagery, Allegory
A Very Stylistic Symbol
Yeah, yeah. These aren't symbols, per se, but it's safe to say that every time you see misplaced capitalization in Winnie-the-Pooh, Milne is emphasizing something. Consistent with his valuing literacy and signs (check out "Signs") as a mode of communication, his use of capital letters upends our usual expectations as readers when we see capitals.
We typically think of capitalized words as reserved for proper nouns, or the beginning of sentences. Since he throws them into the middle of sentences, Milne essentially turns a whole lot of everyday phrases into proper nouns.
For example, as he climbs the tree in Chapter 1, Pooh sings a "Complaining Song" (Winnie-the-Pooh.1.34). By capitalizing this phrase, Milne essentially creates an official title for this category of song. This is not just a song in which Pooh complains. Nope, it belongs to the broader realm of Complaining Songs. Just like "Luncheon Time" (Winnie-the-Pooh.3.46) or a "Special Outdoor Song Which Has To Be Sung In The Snow" (House.1.16).
Too Much Of A GoOd ThInG?
We think not. The distinctive thing about Milne's capitalization is that He Uses It A Lot. The emphasis created by the capitalization shows How The Characters Understand Their World, and mimics The Way Children Learn. That is, kids like to categorize things. It helps create of set of rules help them understand the world, until something comes along and changes the rules or until they develop the capacity for nuance.
Milne shows us this by creating such categories that are overly specific, like describing "just the day for Organizing Something, or for Writing a Notice Signed Rabbit" (House.5.1). Milne also likes to show us how these categories are created.
For instance, check out the chapter in which it's shown that Tiggers don't climb trees. Pooh and Piglet see Tigger and Roo up in a tree and mistakenly think that they're Jaguars. What does a Jaguar do? Well, explains Pooh, they hide up in trees and drop on people, because they're "very good droppers" (House.4.93). This makes such a strong impression on Piglet that he creates a new category of beings for himself. His next thought is that being under a "Very Good Dropper would be a Mistake" (House.4.94). So the capitalization shows us what's really important to our characters, how they understand the way things connect to form broad categories and concepts.