[R] pull stat out of summary

[Evan Cooch]

Continuing my learning curve after 25_ years with using SAS. Want to 
pull the "Mean" forom the summary of something...

test <- rnorm(1000,1.5,1.25)

hold <- summary(test)

names(hold)
[1] "Min."    "1st Qu." "Median"  "Mean"    "3rd Qu." "Max."

OK, so "Mean" is in there.
So, is there a short form answer for why hold$Mean throws an error, and 
hold["Mean"} returns the mean (as desired)?

Silly question I know,  but gotta start somewhere...

Thanks...