Here's some stuff I typed in about walking meditaion from the Visuddhimagga on E-Sangha a while ago:http://www.lioncity.net/buddhism/index. ... &p=1004704Chapter XXPurification of knowledge and vision of what is the path and what is not the path.
This is in the Understanding section, which comes after Virtue and Concentration (which includes the 40 meditation subjects such as kasinas, foulness, body, breath, divine abidings).
It is in a subsection that starts:
XX,45. ... Anther comprehends formations by attributing the three characteristics to them through the medium of the material septad and the immaterial septad.
Taking up and putting down; Growth and decline in every stage; Nutriment; Temperature; Kamma; Consciousness; Natural materiality.
The walking part includes:
XX, 61. ... he again attributes the three characteristics to that same materiality by means of moving forward and moving backward, ...
XX, 62. Next he divides a single footstep into six parts as 'lifting up', 'shifting forward', 'shifting sideways', 'lowering down', 'placing down', and 'fixing down'.
XX, 63. Herein lifting up is raising ... shifting sideways is moving the foot to one side or the other in seeing a thorn, stump, snake and so on ...
XX, 64. Talks about which elements dominate in which stages:
Lifting, moving: air and fire;
Lowering, placing, fixing: earth and water. ... He attributes the three characteristics to materiality according to 'disappearance of what grows old in each stage' by means of these six parts into which he has thus divided it.
XX, 65. How? He considers thus: The elements and the kinds of derived materiality occurring in the lifting up all ceased there without reaching the shifting forward ... Thus formations keep breaking up, like crackling sesamum seeds put into a hot pan; wherever they arise, there they cease stage by stage, section by section, term by term, each without reaching the next part: therefore they are impermanent, painful, not-self.
XX, 66. Talks about how this insight becomes subtle, with a simile of the burning down of a lamp wick ... the flame in each inch, each half inch, in each thread, each strand, will cease without reaching the other strands: but the flame cannot appear without a strand.
This is essentially what the modern Burmese (Mahasi Sayadaw, U Pandita, etc) meditation teachers instruct regarding walking and the rise and fall of the abdomen (which they analyse in this same way - they don't consider it as "breath", since the VM has breath listed as a concentration rather than insight practise).