Right at the downbeat, the orchestra is immediately quick, crisp, and percussive. This part goes by quickly, but what’s happening is that the timpani and lower instruments play only when the higher violins & horns aren’t playing, & vice versa. (The midrange instruments are left out here, to accentuate the difference between the extreme upper & lower ranges.) Together, they play a steady stream of eighth notes, but jumping back & forth between higher & lower instruments, which creates excitement. And we’ll hear a harkening back to this rousing opening, at the very end of the piece.
After those exciting first four bars, you’ll hear the two oboes introducing the main theme. That theme is in Locrian mode.

Keep your ears open, for this intriguing theme being broken up, altered, and passed between instruments. It happens through the whole piece.
Now, let’s talk about the rhythm. The way the composer has used rhythm in this piece is really quite fascinating.
Those first 4 bars set up an alternating rhythm which you’ll keep hearing: alternating bars of 3/4 & 6/8. (Count 123123 | 1&2&3& | 123123 | 1&2&3&)
In fact, the piece is almost entirely in triple time, but keeps switching between the different time signatures 3/4, 3/8, 6/8, and even 9/8. (Which are counted 1&2&3&, 123, 123123, 123123123)
Just try counting along with the music and you’ll see what I mean. It’s delightfully complex. A few non-triple time signatures crop up around the 2-minute and 4-minute marks. After that, it settles into a simple 3/4.
The last four bars echo the very beginning, alternating rhythm and quick theme cleverly combined, bringing the piece to a dramatic conclusion.
Why Fantasia? Heidari says that he chose the title Fantasia to refer to an imaginative musical “idea,” rather than to a specific compositional genre.
There is no specific story behind it. I have tried to echo the minds who have experienced significant life changes, such as leaving their homeland behind or being detached from their roots for any good or bad reason.”
He also says that this piece “reflects the wide range of music that I was listening to, during the creative process, from Bach to Metallica.