An annual assessment is based on the calculation of qi, i.e. the energy present in the property (residential or office building and each room in particular) in a given year. Qi patterns in the environment change from year to year. The Chinese were not the only ones to notice this. Heraclitus of Ephesus (540–480 BC) stated that "Everything flows, nothing stands still" ("Panta rhei kai ouden menei"). Annual influences affect health and wealth, among other matters. An annual assessment allows to maximize the potential of a given year and to reduce any potential risk.