A good answer might be:

• Set each page with movable type and print as many books as you want with ink on paper.

"Simple" does not mean primitive. Carving letters in stone may be primitive, but is it certainly not as simple as setting type. Carving a block of wood for each page is simpler than cutting stone, but each letter of the entire book has to be individually carved. The tools and materials might be simple, but making the books is not. The simplest method is the most advanced: setting movable type. The individual pieces of type are simple and easy to produce, and can easily and reliably be used many times for different pages.

Notice the paradox that civilization and technology had to advance before simple movable type was possible. The computer revolution (ca. 1950--) is often compared to the Gutenberg revolution (ca. 1450--).

Review the advantages of binary:

1. Simple; easy to build.
2. Unambiguous signals (hence noise immunity).
3. Flawless copies can be made.
4. Anything that can be represented with patterns can be represented with patterns of bits.

Unambigous Signals: Consider Paul Revere, waiting for news of the attack of the British troops. He is expecting to see a signal lantern put in the tower of Old North Church which will tell him how the British are attacking:

1.32456 if by land, 1.71922 if by sea.

Lack of ambiguity can be a tremendous advantage. The signal that Paul Revere was actually waiting for that night in 1775 was:

One (lantern) if by land, Two (lanterns) if by sea.

QUESTION 4:

Why can a Chinese abacus be regarded as a "digital computer."