Caption: A schematic diagram illustrating the Ptolemaic magnitude system.

Features:

1. Ptolemy (c.100--c.170 CE) is usually credited with having invented historical magnitude system which is the origin of modern magnitude system. However, Hipparchus (c.190--120 BCE) may have invented it about 300 years earlier.

2. But whoever the inventor was, Ptolemy in his Almagest rated star apparent brightness in 6 magnitudes: 1st, 2nd, 3rd, 4th, 5th, 6th.

3. Ptolemy's classification was by qualitative comparison.

4. 1st was brightest, 6th was barely discernible to the naked eye.

5. You see the problem, the magnitude scale runs the wrong way---brighter is lower, dimmer is higher.

   This wrong-wayness has never been fixed even though the magnitude system has been modernized. It's an endless source of confusion.