Broadly speaking, there are only two categories of knowledge. The experiential and the empirical. Let us look at a very common substance, water, as an example to see the distinction.
Experiential knowledge includes our personal experience of its different states and properties that includes not only how we perceive it through the senses, but also the memories, emotions and feelings with which we respond to it.
By contrast, empirical knowledge is water’s materiality, its chemical composition as revealed by the experimental methods of the founder of modern chemistry, the French genius Antoine Lavoisier. He it was, who in 1783 sparked the two gases of hydrogen and oxygen in a test tube, to find a residue of dew-like drops that “seemed like water”.
Both of these forms of knowledge are equally REAL. The fact (and beauty) of a snowflake melting in the palm of the hand is every bit as important as the scientific explanation that its melting involves the loosening of the lattice holding the molecules of hydrogen and oxygen together.
The modern scientific world tends to favour the latter perspective, whereas spiritual knowledge is based firmly on the former.
Spiritual truths can never be fully explained, they can only be experienced and realised as they are to be discovered beyond the reaches of the mind and the senses. In our meditation and spiritual progress, it is our very own experience which will teach us everything we need to know. From my own experience, I find this to be immeasurably more real and convincing than any amount of words – either spoken, read or proven in a book.