See below for Mostly early Theosophical writings concerning Meditation
"With regard to what I have just called the two great methods in Yoga, we find that by one of these one treads the path of knowledge by Buddhi—the pure reason; and the other the same path by Manas—the concrete mind. ... ... ... But what of the third? What of the will, of which Ahamkara is the representative in cognition? That certainly has its road, but it can scarcely be said to be a “method”. Will breaks its way upwards by sheer unflinching determination, keeping its eyes fixed on the end, and using either buddhi or manas indifferently as a means to that end."
"Along such lines you can learn to bring into control your mind, to discipline your vagrant thought, and thus to reach illumination. One word of warning. You cannot do this, while you are trying meditation with a seed, until you are able to cling to your seed definitely for a considerable time, and maintain throughout an alert attention. It is the emptiness of alert expectation. not the emptiness of impending sleep. If your mind be not in that condition, its mere emptiness is dangerous. It leads to mediumship, to possession, to obsession. You can wisely aim at emptiness, only when you have so disciplined the mind that it can hold for a considerable time to a single point and remain alert when that point is dropped."
Annie Besant, An Introduction To Yoga