Taxation Law Conundrum: Section 14A's Ambiguity

Arre, I'm so lost in Section 14A of the Income-tax Act! Papa always says law is complicated, but this one takes the cake. It says no deduction shall be allowed for expenditure incurred by way of revenue expenditure, which is not wholly and exclusively for the purposes of our business. But what about incidental expenses? Does it mean we can only deduct expenses that are 100% essential for the business? And what's "wholly and exclusively" even mean? The explanations in the textbooks don't help - they just create more confusion. Is it just me or is Section 14A completely contradictory? I've seen papa deal with such ambiguities in court, but I want to understand it first. Can someone please help me out?