It is conventional, though not modern and widespread, to capitalize the initial letter of each opening word in a line of poetry. When represented on the page, poetry has historically been separated from other creative forms in this manner, and writing it in this manner is still often taught in primary and secondary schools. Some poets, especially those of the early modern period, preferred their poems to be read as prose; they used lower-case letters and sometimes even mixed case (capitalizing some words but not others) to avoid monotony. Today, many poets include all their work in one continuous text without any capital letters at all.
Consequently, for readers to distinguish between parts of the poem, some form of punctuation is needed. The most common device is a full stop or period, followed by a comma. These are called punctuation marks because they "point" the reader down different paths within the text.
Without these marks, reading the poem would be difficult if not impossible. For example, when reading "I think therefore I am", it is unclear whether the first part refers to Socrates or Plato. With the addition of periods after every line, the reader knows that "I think" applies to Socrates and "therefore I am" applies to Plato.
These two quotes are from ancient Greek philosophers Socrates and Plato.
Traditionally, the initial word of each line of poetry is capitalized as well. This is called "accenting the iambic pentameter." Today, this is only commonly done with free verse.
The first line of Shakespeare's sonnets and some other poems is not capitalized. These poems are called "unaccented lines."
The first line of a poem is important. It sets the tone for the poem, telling us what kind of language we should expect to find there. If we encounter uncapped lines in a poem, it is a good indication that the author is not following any particular rules about how words should be treated.
Every new line of poetry should begin with a capital letter. Poems have traditionally followed the same capitalization rules as prose, with the distinction that each line begins with a capitalized letter. Some current writers choose not to capitalize every new line, although this is still the widely recognized practice. The decision whether or not to capitalize a new line of poetry is up to the writer or speaker.
Beginning each line with a capital letter is important because it gives the reader or listener a signal about the importance of the information being conveyed. If all the words were lower-case, then they would be considered unimportant. Beginning each line with a capital letter tells the reader that we are starting off with an important idea and that everything after this point will follow in order of significance.
Poets often choose to begin their poems with a capital letter for two main reasons. The first is tradition. As mentioned above, beginning each line with a capital letter is an important part of manying poetry. It lets the reader know that this is not regular prose but rather a special form of writing. The second reason is that doing so helps the poet focus on one idea at a time. If he or she began each line with a lower-case letter, then they would have to think about how to best divide their thoughts into lines. This would likely lead them to write several different sentences or paragraphs instead of just one!
The beautiful thing about creating a poem is that you can do whatever you want with it. Some poets capitalize the first letter of each verse. Some poets use capital letters to indicate the beginning of a sentence in a poem, much as they do in a tale. The usage of caps down the side all the time might disrupt the flow of the poetry. But it's up to the poet how they want to structure their work.
Caps are used this way because it helps to identify which words are poems themselves and which aren't. If you don't cap your lines, someone could write a whole poem made out of just capitals!
Caps also help to set apart important words in a poem. For example, if you were writing about a battle, it would be useful for readers to know who was killed, who was wounded, and so on. By using lower-case words after punctuation, you could end up with a lot of confusion about what part of the story things like "and" and "but" are. Using caps after punctuation ensures that no one mistakes these for normal sentences and ends up telling someone to go jump off a cliff or something.
Finally, capitals are used at the beginning of a line to indicate that it is a unit of the poem. So, a capitalized word at the beginning of a line means that you should think of it as one piece of poetry instead of splitting it up into separate words.