itunes question
 

i started adding music to my external hard drive to save space on my machine, but when i add to library, go find the folder on the external, it basically just copies over to my machine. so kinda defeats the purpose of having it on my external. i read you can move all your music to the external and point itunes to it, but if i don't have the external on me then i won't have any music. is there anyway to set itunes to look on the external and on the machine at the same time, just depends on where the file is located?