Merchant of Venice

I came across the following quote, said to be taken from the Merchant of Venice:

わくわくするのは追いかけている時の事さ。それに比べりゃ、後の楽しみなんて小さいものよ。

Click to expand...

I do not understand this quote.
I tried finding the exact lines in which it appears, searched for it in the text (probably a different translation) and tried to find the english equivalent but to no avail.
Can you please help me understand it, in English, in Japanese or by pointing to the exact place it is written in?

All things that are,
Are with more spirit chased than enjoy'd

I understand now, thanks a lot.