If you know the physics as well as the aesthetics of music it helps. Here it would take too long to cover all of this however here's a start.
Suppose an amateur wanted to tune a piano and all they had was a tuning fork. For simplicity let's say it sounds middle C.
The amateur who has an excellent musical ear but has not undergone a year's training as a piano tuner, proceeds as follows:
(1) Tune middle C on the piano to the tuning fork
(2) Tune all the other Cs on the keyboard to be perfect octaves from middle C. So far so good but what to do next? Let's continue as follows.
(3) The next 'purest' interval after an octave is the perfect 5th. So tune all the Gs on the piano by ear to sound perfectly in tune with the Cs. Everything sounds great.
(4) Assuming we have all the Gs in tune we can go up another 5th to D, excellent.
(5) Go from D up a perfect 5th to A
(6) Continue the process, A to E, E to B, B to F#, F# to C#, C# to G#, G# to D#, D# to A#, A# to E# (which you might be tempted to call F but let's not), E# to B#. Now we're on B# so hurray! we'are back to C because "B# and C are the same" - yay you have completed the circle of 5ths.
So now you have tuned every single note on the piano simply by octaves and perfect 5ths.
Present your work to a pianist who sits down to play. They will produce the most appalling racket that you, they or anyone else has ever heard. The result will be slightly less unpleasant if they play simple tunes in C major but the key of F# will be completely unlistenable.
Why? Because of the mathematics. If you go up in 5ths indefinitely you will actually never end up perfectly in tune no matter how many times you go round the circle of 5ths. This has to do with logarithms so if you don't like maths don't pursue that line of enquiry.
There are other threads that go into more detail, e.g. Why is the perfect fifth the nicest interval?