well, let's define what you mean by 'visualization' first. these terms tend to get confused a bit, so a bit of definition would be in order. if you're talking about memory let's call it recall. you can recall a picture of something, a field, a house, or whatever. but if you're talking about a mental image picture that you create, let's call it a mock-up. you're mocking it up, creating it and looking at it. thus, we're dividing up the two types of what i think you're calling 'visualization', one being a recall or memory and the other being one you create, a mock-up.

both are similar in nature, being mental image pictures. it's just that one is recalled from memory, which is a sort of automatic mock-up maker, making images all the time on auto-pilot, and the other is something you create by your own volition in present time. artists do this all the time. they'll 'mock-up' an image as a guide to what they wish to paint. they see it in their mind. they create it in their mind. this is typically, or simply what we call 'imagination'. one can imagine a red ball in your own mind and see it. this is a mock-up. one could also recall having seen a red ball in the past and see it again in the mind. one could even mock up a red ball, unmock it and then recall having mocked it up and see that. get's tricky, doesnt it :)

now, if by 'visualization' you are talking about mocking up items to see, i doubt there is a limit to this. and certainly, if you saw a million grains of sand on a beach, you could also recall having seen them and thus could 'visualize' or recall having seen them.

i suspect, however, that what you may be trying to ask here is not the seeing of items in your mind, but conceiving the numbers involved; wrapping your head around what a million is by 'seeing' it. i've talked to folks before that have trouble getting the concept of what a million is, as if this were an abstract or something. it's like they're trying to 'hold' within their mind, a million things, and conceptually grasp this many things as a whole. and if that's the case, it's not that hard to do, but it does take some practice.

the secret is to do one. do this until you can do it comfortably. just mock up one of something, a grain of sand, a dot, a ball, whatever. then do two. do that till you can do it comfortably, then do 4. as you climb up the scale of numbers, it's sometimes easier to compartmentalize these things. put 10 balls in a box in your mind and hold it till you can do that, then double the number of boxes with 10 balls. at any time you feel you can handle it, raise the number of balls in each box. make it 20 in each, 100 in each and so on. raise the number in each box and raise the number of boxes. when you can do this comfortably with a million (or whatever number you set), you'll 'grasp' what a million truly is.

i used to do this with large soybean fields or corn fields. i'd try to imagine how many kernals of corn or number of beans in the field there were by both observiing the fields in reality and then within my mind. it's staggering how high you can actually go. a billion is actually a rather small number when you start dealing with values which exist in this universe... or even with soybeans extant in a field :)

and one last note on this; you'll tend to find after a while, that these values tend to be more related to space than to matter when you start getting into larger numbers. just something i've noticed.

K.