### An Introduction to Calculus

for Ann Greenfield

The first lesson is a confusion of symbols

and meanings. Where algebra was once enough

to describe driving five dark hours

from New York City to the Berkshires,

now a different understanding is required.

Even simple exercises pose difficulties:

sift the text of your life together

down to a handful of photographs,

then explain the changes that connect them.

No one gets it at first. Even after weeks

of differentials, you resist the limits

that prove the continuity of change.

In a failing of heart, you imagine only

that New York is immeasurably far

from upstate Massachusetts, regardless

of the journey that once joined them,

or that the ball, lost in the tall grass,

forgets the imperfect parabola of its flight.

But now the new math works to explain

a dance piece, whose movements first frame,

and then disembody the dancers.

In class, the physics of familiar objects,

set flying by these new-found forces,

yield the first fruits of the new analysis:

Here is the moment the ball pauses

before falling, and these are the paths

the planets trace through the heavens.

Just as the world is deconstructed

into this different and changeable nature,

the lessons shift to a sort of addition

that measures velocity to find position.

Whose exercises seem by turns trivial

and ontological: derive the meaning

of the dance from the sum of its movements,

or show how the distance the ball travels

depends on the wind and the moon.

Yet in these last weeks, something else

accumulates in these figures: a safe return

from a fledgling’s journey, a sense of self.

Neither planets whose paths barely curve,

perturbed by other bodies, nor motes

borne up by the rough flood of the air,

but these two natures are joined in us

and we must reconstruct our hearts

for these hard changes to fit their parts.

By Jack Boatwright