Reuven Tsur is most often credited for making the distinction between a literal and a cognitive approach to poetry. According to Tsur there are two ways of reading poetry: for the literal meanings and for the rhythms and sounds that  work on the body and brain and cause us to make connections less directly. According to Tsur most poems have a cognitive aspect to them. 

However, in comparing Walt Whitman's poems "Facing West from a California Shore" and "Beat! Beat! Drums!" it's easy to see that "Facing West from a California Shore" is more literal than "Beat! Beat! Drums!" 

When we read "Facing West from a Caliofrnia Shore," we're told of the speaker's emotions directly. Some examples of telling are:

Facing west from California's shores/

Inquiring, tireless, seeking what is yet unfound,

...

Now I face home again, very pleas'd and joyous

True, you can look at the rhythms of phrases and placements of commas and feel that Whitman is writing down the rhythm of the sea. These rhythms are not foregrounded, however.

By contrast, "Beat! Beat! Drums!"  makes its point mainly through the rhythms and sounds of words. The line

Beat! beat! drums!—blow! bugles! blow!

Make no parley—stop for no expostulation,

Mind not the timid—mind not the weeper or prayer,

Mind not the old man beseeching the young man,