Weight of coins and price of silver during the time of Trajan

[Paddy]

In the book The Coins of Rome - Trajan by Daniele Leoni one can read the following:

... it is important to note that the large quantity of gold released onto the market after the Dacian wars lowered the price of silver.

I don't understand this; shouldn't the price of gold go down because there is more of it? Shouldn't the price of silver go up?

The full passage reads: ... it is important to note that the large quantity of gold released onto the market after the Dacian wars lowered the price of silver. In order to maintain the time-honoured proportion of 25 denarii to the aureus (...), Trajan was forced to reduce the standard of silver in the denarius, lowering from roughly 90-95 % to 80-85% without however altering the weight which remained (...) the same after Nero's reform.

I do not understand why the price of silver went down. I know it should be apparent from the text, but to me it isn't.

If anybody would care to enlighten me, I'd appreciate it.

[glebe]

Good question. I would have presumed (perhaps simplistically) that Trajan reduced the silver content of the denarius because its price against gold had risen, not fallen.
Actually, this raises an interesting question, namely whether gold or silver was the basis of the currency.
Also, if the value of gold fell, and the denarius was devalued to match it, then it would seem  that the value of both the aureus and the denarius must have fallen in terms of other goods. Did this actually happen?

Ross G.