We can cite another example – of the sweetness of a mango and a lump of sugar. Both are sweet; but how does one define each sweetness? It is not possible for anyone to do that in words and there is only one way to distinguish the nature of each. One must eat the two things and know for himself what the difference is.
In the same way, it is not easy to define the inner excellencies of man. For instance, humbleness is difficult to describe. However, if one meets a humble person and observes his conduct and stays in his company for some time then that characteristic will grow in him. Hence, it is necessary to turn to a Shaykh and live in his company to know about tasawwuf and sulook. These things cannot grow in anyone by merely talking about them. It is only by attending the company of and giving one’s time to a Shaykh that Allah Ta’ala helps one attain these things.
Spiritual Discourses by Mufti Taqi Usmani