You can liken time to a river and the point you are in time to a bridge over the river. Upstream is time to come . Downstream is time gone by. Water under the bridge is time now. As the river and time are in constant motion, now is so fleeting a moment that it hardly exists.You can not really capture, now, to look at later even with the fastest camera or freeze the river . As by the time you have had the thought , now , has already gone and been replaced by a new , now . Best you can do is save a memory of that , now. It will not be the full , now , just as you could not capture all the drops of the river that made up that , now. If , now , is that important a memory will have to suffice. Thankfully we can not capture or hold on to, now ,for we would surely hold on to a , now , that was so important to us but by doing so we would loose all the , nows . that came after and become stuck in time like a fly in amber.
I should really have said " It's all just water under the bridge" or where I was brought up " water under bridge" meaning it is in the past and best forgotten.