When I was just a wee little lass, I spent a lot of time in libraries. There were two, conveniently located on my way to and from school. I can still clearly remember the way the light slanted in through the windows as I walked through the non-fiction section, looking for a book on costumes (I can't remember why I was looking for costume books), and I found...
Patterns of Fashion: The Cut and Construction of Women's Clothes, 1680-1840, by Janet Arnold.
Specifically, the 1775 polonaise. Something about the striped pattern and the silhouette captured my attention. The neat diagrams certainly helped, too. I checked the book out, made some photocopies, coloured some of those copies, and set about with grand dreams.
It's been over 15 years since I first saw that dress. It's the one that started all my love of historical costumes. I'd been to a few SCA events before that, but the kind of outfits my mum had made for me did not satisfy my then-unknown love of structure. I was not yet a proficient seamstress. I'd made a few things for school, and a Star Trek costume, but I hated sewing. Still, I had visions of one day wearing a big floofy gown.
Fast forward some 4-6 years. I can also remember the way the light slanted through the windows of my apartment when I found Katherine's website, and specifically a green polonaise that she'd sewn entirely by hand. I was blown away by A: how pretty it was, and B: that she'd had the patience to do it by hand. I hated sewing by machine! It took so much time! The idea of doing an entire outfit, by hand, blew my mind.
Shortly after this, I got into gothic lolita fashion and started learning to love to sew. Not too long after that, I started going to local conventions, simply to have an excuse to wear a costume out in public.
Somewhere in there, I fell in love with Victorian fashions. I think I loved them for the same reason I loved that polonaise. They have a similar silhouette: the heavily structured bodice, full skirt, "business in the front, party in the back" skirts. Victorian is my prime area of costuming, as there are great, commercially-available patterns. Late-18th century seemed a little harder for me to get into, with not as many patterns available. Even though using Japanese pattern books for gothic lolita taught me a fair amount about drafting patterns, the incredibly-necessary fitting of Georgian gowns still seemed too far out of reach. I did make a Butterick pattern one year, but I didn't make any of the underpinnings, so I was always afraid of ripping it in some horrible way while wearing it.
Over the years I've expanded into other areas of historical dress. I fell in love with Elizabethan, then Tudor costumes. I got into cosplay. I started going on a local attraction even though it's not all THAT interesting and kind of expensive, simply because I have an excuse to wear a new Victorian gown every year.
I'm not really sure when I came back to the late 18th century. I read a few blogs of costumers that cover many eras, and I always find myself loving their 18th century outfits and wishing I a: had one to wear, and b: somewhere to wear it. I have the same feelings about Civil War era gowns, though at least for those, my Victorian group would be easier to fit into.
I decided quite recently that it didn't matter that I technically have no event I can wear a dress like this to. Eighteenth century was my first true love of historical fashion. Therefore, I will make a dress.
And it will be beautiful.
ETA: American Duchess has a great article on how she "found her era". Mine would probably be Victorian bustle as that was the first era I started sewing for. I've been known to tell people to just give me time and enough images of an era I previously haven't considered, and in time I will probably come to love it as much as Victorian ;)