Contemplating and noting, and how consciousness arises at the moment of smelling
In the case of ordinary worldlings, every time an odour is smelt, the sense of smell - the nose organ (rupa), and the odour are wrongly thought of as permanent, pleasurable and good and an 'atta' (being). This is ignorance (avijja) not knowing what they truly are. Based upon this ignorance, miseries and sufferings such as sankhara-vinnana, etc., occur.
A Yogi who is contemplating and noting as "smelling", "smelling" every time an odour is smelt, when the power of his concentration becomes highly developed, will come to know distinguishably that the nose and the odour (rupas) are different from the 'smell', and that the consciousness of smelling is also another. They are known as being different from one another. The nose, smelling, the odour, and awareness through contemplation are found to have vanished and ceased altogether after becoming aware of what has taken place. Hence, realisation comes that these are by nature 'impermanent', 'suffering' and 'Non-Self' (anatta). This is the genuine Vipassana insight-knowledge that penetratingly knows the truth of the characteristics of anicca, etc.
How such awareness takes place may be recited as follows: