Well, of course, you never saw him. He's invisible. Except for his shadow.
10 seconds sound clip from the Jack Frost (1979) movie soundboard.
You can hear this line at 00:02:47 in the Blu-ray version of the movie.
Quote context
[...]
- Heh heh heh. They'll never catch on up there.
- That's a magic shadow. It belongs to Jack Frost, not me.
- Then he gets 6 more weeks of winter fun, and I get a bit more shut-eye.
- Well, of course, you never saw him. He's invisible. Except for his shadow.
- Nobody's ever seen Jack Frost. Unless you count that one time when he became human.
- Even if you never saw him, you have seen his work.
- You wake up one morning and you know that something's new.
- The windowpanes are frosted, and the sky's a blinding blue.
- There's not a bird out singing, and the ground is white with snow.
[...]