Forty-three is prime and reduces to seven. It is one of the clearest cases in which candour is the only honest treatment: the number carries no traditional religious symbolism worth reporting. The older systems developed the small numbers, the notable primes and the round figures, and passed over most of the integers in the forties, forty-three among them. What can be said is structural, it is prime, it is the sum of the first three odd primes, three, five, seven and others in various arrangements beloved of recreational mathematics, but none of this amounts to lore.
Where the older symbolic systems left forty-three undeveloped, Cheiro's 1926 Book of Numbers gives it one of the most severely negative readings in his whole compound-number scheme, a distinct description in its own right rather than a pointer to a lower number: symbolised by revolution, upheaval, strife and failure, and judged an unfortunate sign wherever it appears in calculations relating to future events, a caution his book states without softening. In chemistry, forty-three is the atomic number of technetium, notable as the lightest element with no stable isotopes at all; every form of technetium is radioactive, and it was the first element ever produced artificially rather than found in nature, isolated in 1937 by Carlo Perrier and Emilio Segre.