"Which," I eventually said - running out of breath - "will be like an investment in life, if you really think about it. And who doesn't want to invest in life? You want to invest in life, right, dad?" I looked at him triumphantly. Who doesn't want to invest in life? My argument was water-tight. "So," I finished: "what do you think?"
Dad looked at the television with a completely neutral expression.
"No," he said after a pause.
"No?" I echoed. There was a silence while I waited for him to change his mind. He didn't. "NO?" I repeated again, a little more loudly.
"No," dad said.
I stared at him for a few seconds - did a few calculations in my head: went through my argument again and confirmed that it was infallible - and then spluttered: "why the hell not?"
"Because," dad replied impassively, "I'm not buying into any more of your hare-brained schemes. You have them every day. How long did you spend thinking about this one?" He looked at me sternly. "From beginning of idea to sitting here and telling me about it, exactly how long did it take?"
"A considerable amount of time," I said with dignity. "Considerable."
Mum, who had been sitting quietly - for her - in the armchair, then decided to pipe up with:
"three hours. She came rushing down the stairs gabbling about teaching English abroad at 3pm, and it's 6 now."
Dad looked at me again, while I glared furiously at mum.
"Three hours," he repeated. "Three hours, and you want £1,000 to do a course. That''s £333 for every hour you spent thinking about it."
"A course that will change my life," I said, standing up: furious. "I can't believe the lack of support around here. Jesus! What do I have to do to get a bit of belief?"
"Tell you what," dad said calmly. "You write it all down, and then come back in two weeks. If, in two weeks time, you've looked at all the options and you genuinely believe that this is what you want to do, then I'll lend you the money."
"Fine!" I cried emotionally. "Great! I'll see you back here in two weeks then!" And then I stomped to the door. "What time is dinner?" I added.
"Fifteen minutes," mum said.
"Okay," I sulked: "see you in fifteen minutes." And then I left the room to go and play my music in my bedroom too loudly.
As I lay on my bed, I was absolutely furious: my argument, I thought, was absolutely sound. It would give me a qualification that would let me teach English in any country I wanted, and would therefore free me from the shackles of unemployment and general misery in Welwyn Garden City. What was there to question?
Except, I thought, that I don't really like teaching. Never have.
And I might get bored, because I love my own language too much to peel it down to the bare basics over and over again.
I stared at the ceiling.
And I'm not sure I like kids much.
And where would I live? Did I want to sign a contract in a strange city with no friends, and then stay there? Did I want to rent a place in a country where I didn't speak the language, when really I just wanted to pass through? Wouldn't that be almost as bad as teaching a class full of children here?
I stared at the ceiling for a couple more minutes.
£1,000 was a lot of money. You could do quite a lot with that. You could actually buy a round the world ticket with that. And you wouldn't have to teach at all.
Hmm.
And, actually, if I really wanted to teach abroad, I could do it for free. Or - if I was desperate - look for something that would take me anyway. I have a Masters degree in the bloody subject, after all.
I pouted for a few minutes, and then I went back downstairs.
"Dad," I said. "I've been thinking about it, and maybe I need to think about it a little bit harder."
"Right," dad said. "Fair enough." It looked suspiciously like his mouth was twitching, but I ignored that. His mouth often twitches when I'm talking, and I have no idea why.
"It's not that it wasn't a great idea," I pointed out. "But maybe it wasn't the...erm... right idea for me. Maybe."
"Fair enough," dad said again. "Keep me in the loop if you have any more ideas. One of them might be one you want to stick to."
And, as I turned to leave the room, I could have sworn that I saw him winking at my mum.
It's not dangerous to have hare-brained schemes, as long as you have people around you who can tell the difference between the good ones and the bad ones; between the ones that have a chance of working, and the ones that haven't got a hope in hell.
As annoying as they are, thank God I have those people. Or I'd probably just float away.
Anyway, if that idea doesn't feel right, then there are plenty more that might. Now I just need to think of them.