Essential oil chemistry is a part of organic chemistry, which covers a vast
range of compounds. Early ideas suggested that organic compounds were all
obtained from either plant or animal sources, i.e. that they were natural products,
and arose only through ‘vital forces’ inherent in living cells. This definition
is no longer true as a result of modern laboratory synthetic methods. The
modern definition of organic chemistry is that it is the chemistry of covalently
bonded carbon compounds.