Polio vaccine is usually provided in vials containing 10–20 doses of vaccine. A single dose of oral polio vaccine (usually two drops) contains 1,000,000 infectious units of Sabin 1 (effective against PV1), 100,000 infectious units of the Sabin 2 strain, and 600,000 infectious units of Sabin 3. The vaccine contains small traces of antibiotics—neomycin and streptomycin—but does not contain preservatives. In a generic sense, vaccination works by priming the immune system with an 'immunogen'. Stimulating immune response, by use of an infectious agent, is known as immunization. The development of immunity to polio efficiently blocks person-to-person transmission of wild poliovirus, thereby protecting
Necessity is the mother of invention our invention." Jowett's translation is noted for injecting flowery, if not florid, language familiar to his Victorian era audience. Jowett himself, in "Plato's Republic: The Greek Text", Vol. III "Notes", 1894, p. 82, gives a literal translation of Plato as "our need will be the real creator," without the proverbial flourish. In an address to the Mathematical Association of England on the importance of education in 1917, Alfred North Whitehead argued that ""the basis of invention is science, and science is almost wholly the outgrowth of pleasurable intellectual curiosity."" and in contrast to the old proverb ""Necessity is the mother