When I was a boy, I knew I was sneaky, but I didn’t think of myself as a “lowlife sneak” until my mother called me one with such disgust in her voice I actually did feel ashamed.

I was babysitting at the next-door neighbor’s house when my mother looked out her own bedroom window and spotted me, twenty feet away, in Mrs. Hanley’s bedroom. I was sitting on the edge of her bed and reading her Last Will and Testament, which I had found in a bottom dresser drawer. It was not interesting. But the thrill of being sneaky was addictive. I had done a lot of babysitting in the neighborhood. I read Mrs. Hogan’s diary and might have known she was leaving Mr. Hogan before he did. I knew where the smutty magazines were kept—and all their compatible products. I didn’t do anything with what I found — I just liked knowing I had discovered something that was supposed to be a secret.

I was carefully returning Mrs. Hanley’s will back into the dresser drawer when the doorbell rang. I ran to answer the door, and my mother was on the other side. Her first biting sentence was well chosen. “You are nothing but a lowlife sneak!” she hissed.

She had me there. But I was only a sneak of casual opportunity. Besides my babysitting sneakiness, I listened in on other people’s phone conversations, read mail that wasn’t mine, used binoculars to watch people from safe distances, and basically amused myself by ferreting out secrets that were none of my business. But I wasn’t an organized, literary sneak — that is, until I read Harriet the Spy by Louise Fitzhugh.

I came to Harriet the Spy a little late in my reading life. Harriet was in sixth grade and I was in seventh when I first read it, and I wouldn’t have discovered the book at all except that my older sister, Betsy, had it. She didn’t care for the book, but she did say, “You’ll like it. You are a sneak, too.” My mother always confided in my sister, which only allowed my sister to loathe me more than what came naturally to her.

So I read the book. It was an odd read. Harriet creeped me out because I was as emotionally awkward as she was, and it repulsed me to see myself defined through the mirror of that text. Still, the book connected me to one particular activity: Harriet kept a notebook and wrote down secret observations she made while out walking on her “spy route.”

I had a journal (the boy name for a diary), and the idea of an organized “spy route” got under my skin. For the first time I began to draw maps of my neighborhood, and maps of my school, and maps of the inside of people’s homes I would visit or babysit for — and maps of my own home, too. I would annotate the maps and then write short bits about certain characters, objects, or events. I was a stamp collector and coin collector, and so discovering secrets about people and putting them into a book was right up my alley.

See, for example, the map of my home [printed in the May/June 2014 Horn Book Magazine].

Look inside the house and you will see “My Room” (with a picture of my journal). Across the hall was my sister’s room. I once read her diary and she caught me and hurt me badly, but for some reason I didn’t draw that moment. We had one bathroom and I was not allowed to lock the door because my mother caught me taking fake, waterless baths. The “Cool Air Chair” in the kitchen is pure genius — we had no air conditioning in South Florida, and the moment my parents would leave the house I would open the refrigerator, pull up a dining-room chair, get a book, and sit on the chair and stick my feet in the refrigerator and prop them up on a shelf. Now that was great reading! (My mother caught on to me one day because I had gotten too comfortable and kicked my sneakers off in the refrigerator and forgotten to take them out.) “Jack’s Stain” is where I threw up on the wall — it was spaghetti, and we never could get the faint, greasy orange stain off the wall. “Zippy the Roach” was one of my roach pals. I wrote his name on his back with nail polish and Scotch-taped him to a Hot Wheels car, and then made a leash out of thread and pulled him down the sidewalk. Once, when my sister was sleeping with her mouth open on the couch, I dropped him down her throat. She threatened to tell my mom unless I took off all my clothes and ran naked around the house. I opted for the naked punishment. But while I was running, she locked all the doors and windows, and I had to hide in the front bushes all day until my dad came home. “Wart Trouble” is when I ripped a wart off my foot with pliers and lost a lot of blood and it got infected and my foot swelled up to the size of a canned ham and then I broke out in boils. My mother told our family doctor that I was the “stupidest kid in the world.” I broke my little brother Pete’s arm in the backyard. Our cat fell out of a tree and did not land on its feet. An alligator ate our dog. I could go on and on…and if I had more room I’d write about the Pagoda family next door. My mother called them the “low supervision” family, and they taught me a lot of dangerous stunts.

Harriet the Spy started all this business, which resulted in maps and journals full of stories, which eventually turned into five volumes of Jack Henry stories. I’m forever grateful to Louise Fitzhugh for the inspiration. I love Harriet, and now when I read the book I get very upset when anyone is mean to her.

From the May/June 2014 issue of The Horn Book Magazine. Part of a special section commemorating the 50th anniversary of Harriet the Spy.