I want to know the answer to the following question:
After the fifth quark was discovered, Feynman said what had to also exist?
All the background I'm provided with is that "In the mid-1960s, physicists believed that quarks were just a bookkeeping device for symmetry numbers, not real particles, as the statistics of the Omega-minus particle, if it were interpreted as three identical strange quarks bound together, seemed impossible if quarks were real.". Is that enough to answer the question?