What metaphors and similes are used to explain ideas in "If"?

That is a great question!  The fact is that the only way
we can understand ideas or concepts is through figurative speech.  We use metaphors,
similes, and analogies, which are kind of super metaphors, to understand anything
because the only way we can get information in our brains is through our five senses. 
We must see, hear, taste, touch, or smell something, and then we can use that sensory
input to describe ideas and feelings.  Let's take two
examples.

First, how do we understand the concept of
education?  That is a completely intangible idea.  We can only understand it in terms of
metaphor, really.  So we often think of it as a structure, with a foundation.  Teachers
talk about "scaffolding," which means teaching students to learn by connecting with what
they already know.  We talk about "closing the gap" between low-performing and
high-performing students.  These are all tangible "things" that we are familiar with in
the physical world, ways for us to understand what the concept of education
is.

Second, let us look at an emotion, anger.  That is an
intangible idea. But we use metaphors to describe it, metaphors that are based on what
we observe people doing when they are angry.  They "explode" with rage, for example, or
"blow their tops."  They boil over with anger.

Think about
other concepts that you are familiar with, for example, the concept of business, or the
concept of love.  How many metaphors can you think of to describe
these?

I have included a link for you with an excerpt from
Lakeoff and Johnson, a team who write often on this very topic.