Rest at Beginning - Why and How to Use?

In a lot of Bach's fugues, he uses a rest at the beginning. I've never understood why and how to use these. Hoping someone can explain why and how to write a piece using one in the same way, as demonstrated in this picture:

It's a pickup/lead-in. It's like the pitched equivalent of a drum-roll basically.

Sorry... I don't understand.

Couple of reasons. In that example, that's C minor in the WTK book1, right? How would you write that subject without the pause? Remember that it's important which notes fall on which times in the measure, specially the strong beats. So that's one aspect. The other is that because the subject doesn't start with a strong first beat, it's easier to "lead" into it from other voices and motives. It also makes it ideal to use in sequencing, specially the beginning three note motif, which he uses constantly.

Another point is that back in that time, strong beats were usually ornamented on the harpsichord, and maybe he wanted to avoid having any ornamentation at the start to make the subject clearer to hear. In that example if you add ornaments to the strong beats, you would still get the C B C motive relatively clean since you don't tend to ornament fast notes, specially not ones that already sound like an ornament on their own. Instead you could ornament the Ab in the first measure, the G in the second, maybe the Ab in the second too, but less.

Important to remember that this is otherwise inaudible to the public, specially once the piece is already set in motion.

Some melodies just work out that way.  Tap your foot along to some music.  You'll find that there is a "right" way to tap.  You are instinctively feeling where the beat lies.  Listen to the same music again and try to tap on the opposite beats.  It will feel all kinds of weird.  You can tap faster or slower if you want, and it will still work, so that you are tapping on whole notes instead of half notes, or are keeping an eighth note pulse instead of a quarter note pulse, but to tap on the WRONG beats feels unnatural.  

In the example you posted, if you started it without that little rest at the beginning, you would end up with the "tappable" beats in the wrong place.  The measure lines in music combined with the time signature break the music into units, so it's easier to read at speed.  The same way that spaces between words, periods, and paragraph breaks help you read written material.  It puts the information into chunks so it's easier to organize it mentally as your eye skims the page.  Measure lines and a time signature help you "chunk" music, and they don't do it arbitrarily.  They organize it by beats.  By foot taps.  

Usually the strongest beats (or taps) in a piece of music fall on beat one.  ONE two three, ONE two three, ONE two three...  Or in a 4/4 piece, ONE two three four, ONE two three four.  And some pieces have sort of a musical lead in before you get to that first big beat...  two, and-uh, three, and-uh, four, and-uh, ONE.  

For your own work, when you start writing a new piece, tap your foot or clap to your melody.  Underline or circle each note that you want to instinctively clap or tap on.  That will show you where your beat sits.  Now try counting along to them.  Naturally, most music either goes 1,2,3, 1,2,3, 1,2,3 or 1,2,3,4, 1,2,3,4... Write the numbers above the notes where you feel the need to say them.  Now go back and write in a measure line in front of each number one, and voila!  You may find that like Bach's fugue, your piece should have a little rest before the first note you have written.  

On 4/11/2020 at 5:27 PM, Stradivarius said:

Sorry... I don't understand.

Like SSC said, it's about where you want the downbeat to happen.

If I've written the following melody:

I want that D note to begin on the first downbeat of a bar. If it is anywhere else, the rhythm will not be correct and it will totally change the feel and timing of it. How do you make that D note be the first downbeat of a new bar when two eighth notes come before it? Put those two eighth notes in the bar before that D note, of course.

Here it is another way, which should help you further understand the concept.

It's exactly the same as before, only this time: the two eighth notes of A and C are on beat 4 of bar 2. So bar 1 begins on "D". This phrase will loop seamlessly.

This means that, in example #1, bar 2 effectively serves as the real bar #1.

In your bach example, that second C note needs to be on the second beat, but there are two sixteenths before it. Thus, the eighth-note rest offsets it correctly.