What does it mean to watch the mind directly? For instance, if there is a thought to examine whether the mind is calm or thinking of other things, it is watching the mind directly. We should not entertain this kind of examination when abiding in the concentrated state, because once the thought of examination arises, it disrupts this state. Hence we need to watch the mind from the side.

~Depicted from THE FOUR SEALS OF DHARMA - The Practice of Impermanence