Vjylku

I've heard many people say this:

"If you can play one instrument, other instruments will be easy to learn"

I just can't help but wonder if this is true. Suppose I'm a professional flute player. Would learning an instrument, suppose guitar (while being the professional flute player) be simpler to learn than if I didn't play the flute?

You wouldn’t need to relearn theory or reading music. You wouldn’t need to learn to establish a practice regimen. You wouldn’t need to relearn to hear intervals or feel a beat.

Going from flute to guitar, you would need to memorize the positions of notes and chords. You would need to develop calluses. You would have to suffer the pain of learning to contort your hand to make barre chords. It would take a lot of practice to develop the muscle memory you need to play proficiently.

If you’re going between similar instruments—organ to piano, for example—you would certainly be influenced by the techniques of your original instrument. It could be an advantage. Chords are fingered the same on both instruments. But you’d have a set of disadvantages to overcome as well. In this example, you’d have to learn dynamic expression in a whole new way. Suddenly, the force you put on the keys matters in a way it never did before!

The answer definitely depends on what instrument you’re coming from and what instrument you’re going to. But, in general, yes, as an experienced musician, you have a considerable advantage that an absolute beginner lacks.

Well, it certainly won't be easy, but I think it'll be easier than starting as a complete beginner.

For starters, you'll know the musical side of things. Everyone who's played an instrument knows music theory to some extent, and even if you just know what notes are in a scale, you'll have an advantage over a complete beginner. Any music theory knowledge will help one understand more what one is learning. It may seem like there's a longer way to go because you know from learning one instrument what it takes to learn another, but you're closer than you think, and closer than beginners.

For some instruments, there is a bit of correlation in the actual playing. I imagine most keyboard instruments share similar technique and ergonomics, and instruments of the same family are similar to play (like saxophones). I wouldn't count on much of it for flute and guitar, though, besides maybe the fingering aspect being similar.

I play a couple instruments (decently), and I think the most important thing to remember is that each instrument is different, and serves a different role. Keyboard instruments, like piano, can certainly be melodic, but flute is nearly always carrying the melody, and guitarists need to be able to create harmony in a way that pianists don't usually need to learn.

Best of luck in this endeavor!