Upon - On

sxyy66

Upon - On
When do we use upon and when on ; that's the question.
When upon an be replaced by on, as most of the cases it can be, on is usually preferable.
Thus, I put the book upon the table is slightly ponderous for I put the book on the table. However (and there's always 'a however'), upon is as common as on in many expressions. An example: Upon reflection I picked it up again (On reflection I picked it up again). It sometimes comes more naturally as in His schemes, built upon one another for so long, tumbled in disarray. The up in upon is usually not significant and when it is, it would normally be stressed in speech. In that case up on should be used. Example: The moon shone upon the mountain, but we could see a distant campfire up on the mountain.[not in the valley.]