Wren grew into the official keeper of records because she was better organized than Della.
The two sisters argued constantly.
“You wrote this wrong.”
“No.”
“You wrote 3.8 gallons.”
“It was.”
“It was 3.8 gallons per minute.”
“Same thing.”
“No.”
“Yes.”
“No.”
Wren became interested in data.
Della cared about machines.
That difference eventually made them a formidable team.
Opal died when Della was seventeen.
Quietly.
In the room with the pamphlets.
Her last week, Della sat beside her.
College applications covered the table.
University of Kentucky.
Murray State.
Purdue.
Several agricultural engineering programs.
Opal tapped one.
“You going?”
“If we can afford it.”
“That’s not what I asked.”
Della smiled sadly.
“Yes.”
“Good.”
“You always said farming was enough education.”
“I said farming teaches.”
“I didn’t say school doesn’t.”
Della looked around at the pamphlets.
“Can I have these?”
Opal opened one eye.
“I’m not dead yet.”
“Sorry.”
“Thief.”
Della laughed.
The shelves became hers a week later.
For months, she could not open the brown drip-irrigation binder.
Then one winter evening she finally did.
Inside the front cover, Opal had written:
DELLA FOUND THIS ONE FIRST.
PAY ATTENTION TO WHAT SHE PAYS ATTENTION TO.
Della cried.
Harlan found her.
Did not ask why.
Sat beside her.
After a while he said:
“You know your grandmother told me to let you fail that first summer.”
Della looked up.
“What?”
“I wanted to fix half those leaks for you.”
“She threatened me.”
“With what?”
“Wouldn’t say.”
“That’s worse.”
“She said if I solved it, you’d learn the system.”
“If you solved it, you’d learn yourself.”
Della closed the binder.
“Did you agree?”
“No.”
“I was scared you’d flood the soybeans.”
She smiled.
“But you let me.”
“You looked serious.”
Harlan looked toward the dark window.
“Sometimes parenting is figuring out which mistakes are safe enough to belong to the child.”
Della carried that sentence to college.
She studied agricultural engineering.
The first year almost broke her confidence.
Calculus.
Physics.
Fluid mechanics.
Students who seemed to understand equations immediately.
Della understood water in a pipe.
She did not always understand the symbols describing it.
Her first fluid mechanics exam came back with a 62.
She sat outside the engineering building holding the paper.
For the first time, she wondered whether collecting scrap pipe and getting a newspaper article had convinced everybody she was smarter than she really was.
Hannah Lee, now finishing graduate work at the same university, found her.
“What happened?”
Della showed the exam.
Hannah shrugged.
“That’s fixable.”
“I thought I was supposed to be good at this.”
“You are good at systems.”
“You’re bad at differential equations.”
“Currently.”
Della hated the word currently.
It gave failure somewhere to go.
She worked.
Office hours.
Study group.
Tutoring.
Her next exam was an 81.
Then 88.
She never became the top theoretical student.
She became one of the best at translating theory into field systems.
Senior year, her team designed a low-cost irrigation controller for small diversified farms.
Her teammates wanted sophisticated sensors.
Della kept asking: