Why is the smell of perfume not immediately noticeable?

The world of perfumes is a true symphony of scents, where each note plays its role. And, as in any musical composition, to hear the full beauty of the scent, time is needed.

But why can one scent seem light and floral, and then unfold with notes of tobacco and spices. And another can be dense and oriental, and then transform into something delicate and sweet? Is this some kind of magic?