‘From my many years of research on indoor and outdoor housecat behaviour and the human-cat relationship, I can safely say that is important for cats with outdoor experience earlier in life that they have access to the outdoors – one way or the other. That is easy to provide if one lives on the ground floor, but is successively more difficult the higher up in the building one lives. If the cat at one point in its life was allowed, or grew up outdoors, then it shouldn’t be kept exclusively indoors later in life! Sooner or later such ‘captive’ cats usually show behavioural disturbances that tarnish (or even cause the end of) the cat-human relationship.’
[Dennis Turner in: Brigitte Schuster, Architektur für die Katz – Schweizer Katzenleitern, Basel/Bern, 2019, p. 12.]