摩訶止觀 4.135

4.135

今除意，但明於五塵。五塵非欲，而其中有味，能生行人須欲之心，故言「五欲」。譬如陶師，人客延請，不得就功；五欲亦爾，常能牽人入諸魔境，雖具前緣，攝心難立，是故須呵。

Now, excluding the mental faculty, we explain only the five sense objects. The five sense objects are not themselves desires, but there is flavor in them that can generate a practitioner's longing and desire; hence they are called the "five desires." For example, if a potter is invited by visitors, he cannot complete his work; the five desires are also like this, constantly able to drag people into various realms of māra. Although one possesses the preceding conditions, establishing concentration of the mind is difficult; therefore, they must be reproved.