Bagpuss The Gnome:
A more TWIM like approach where you "keep the breath in mind" rather than focus on a tiny spot works well also.
The question still remains how to deepen the absorption though.
Have you looked at
A General, All Purpose Jhana Thread? Starting at this post and moving on as necessary.
When it came time to actually attempting the practice of the jhanas, rather than rely on the somewhat academically dry yet wonderfully detailed description provided by the celebrated Buddhist monk Henepola Gunaratana in his essay "
The Jhanas" (which was an abridged version from his book The Path of Serenity and Insight: An Explanation of the Buddhist Jhanas), I went with a much briefer Internet version I had found which entailed a description written by Leigh Brasington ("
The Jhanas in Theravada Buddhist Meditation"), a noted lay practitioner and jhana teacher, whose description was more accessible to me and seemed to make more intuitive sense.
At this point it may be helpful to gain a better idea about the difference between what ordinary
samadhi is as opposed to what jhana
samadhi is as it is discussed within the context of Buddhist meditation. As I've come to experience and understand it,
samadhi refers to — and has traditionally been defined as — "concentration." What this refers to in layman's terms is the mind's ability to concentrate on, for example, an object like the breath
without becoming distracted (as by interposing thought). Being able to focus on that object in order to examine it for several minutes in succession without distraction or unnoticed distraction. When understood correctly within this context, then,
samadhi takes on a more prosaic and mundane definition and connotation, thus separating it from other contexts in which it may have been viewed as a more glorified state of mind. Gotama the Buddha was nothing if not down-to-earth and practical when it came to describing the purpose of meditation and how he employed it in the process of realization of the Dhamma he taught. . . .
In ordinary terms jhana can be described very simply as "absorbed concentration" or "absorption
samadhi" (what many modern day meditation masters call
appana samadhi or "fixed concentration"). Just how this kind of absorption
samadhi differs from the normal everyday brand of
samadhi becomes evident when one compares the level or depth of concentration that is ultimately achieved while one enters and remains in this state of "fixed concentration."
In normal samadhi, the mind becomes able to remain focused on an object without becoming absorbed in that object. In other words, there is a modicum of effort being made in order to remain in this state. Absorption occurs when the mind finds a particularly pleasant sensation on which to become focused and absorbed, thus allowing the mind to become automatically (and effortlessly)
fixed on the object of observation. The difference lies, on the one hand, in the amount of effort needed (or not needed) to maintain the
samadhi, and, on the other hand, in the perception of the mind's becoming pleasantly (at least during the first three jhanas) locked on the object of observation while having entered the state of absorption. Once the mind reaches the fourth jhana, what remains left of the mental constituents are the two factors of "inner tranquility" and "clear awareness" which was developed during the previous three levels, along with a strong enduring sense of "mindfulness and equanimity."
Because jhana is characterized by its effortlessness, attaining this state makes it the perfect foundation for taking up contemplation of any object or subject that the observer wishes to examine. The mind is still and at ease. It is also able to remain fixed and focused on its object without any trouble, and through a practice of bare attention (meaning not conditioned by personal prejudice or biased views), it is able to discern the true nature of the phenomenon under observation. This is why the Buddha was so insistent in exhorting the development of absorption among the members of his sangha. It provided a major tool for those to use who wished to put an end to ignorance and thus attain awakening in this very lifetime.
The next post,
A Practical Look at Jhana Practice — Part One, talks about methods for deepening this absorption state. Once you are able to achieve the second
samatha jhana wherein the pleasant sensation of being absorbed is carried on
effortlessly, from there it is only a matter of dropping
piti and
sukha to enter the fourth
samatha jhana. You can't get any deeper than the fourth
samatha jhana, because this level is the jumping off point for the attainment of the remaining immaterial
samatha jhanas (i.e. 5th through 8th levels). In other words, in order to attain the immaterial jhanas, you need to be able to enter the fourth, which is as deep as you can go.
From here there may be further important hints that you can pick up about this state that can be learned by a careful reading of
A Practical Look at Jhana Practice — Part Two. Like for instance, the following statement: "My practice didn't really begin to take off until I was able to finally bring the mind to stillness and quietude."
Enjoy.