Anyways, Rabba bar bar Hana decided he would tell his compatriots that he left behind a golden dove, a prized possession, and they couldn't possibly argue with him, for something so valuable, who wouldn't go back to retrieve it? So, he gave them his newly fabricated excuse, and went back up the trail, while they waited for him. Because of Rabba bar bar Hana's great appreciation of the mitzwah, a miracle occurred and when he went back he found an actual golden dove.
Even though I'm often in favor of the literal meaning of stories in the Talmud and the importance of them, I think there's another lesson we can learn from this story. Whether the golden dove he found was actual or allegorical, I think it teaches us about the reward of performing mitzwoth. It seems to me that from this story we see that HaShem rewards us for each mitzwah in direct accordance with how WE value that mitzwah.
If each morning we don tefillin out of the burden of the obligation, so HaShem relates to our action and rewards us also out of obligation, but it is figuratively a burden for Him too. He doesn't want to, but He has to. Instead when we are excited to put on tefillin and experience the spiritual elevation, the closeness to HaShem that this mitzwah brings us. Then HaShem figuratively is excited to elevate us and bring us close, excited to shower us with blessing.
And, with an idea like this, what better way to execute it than be truly celebrating the Shabbath, looking forward to it all week, preparing for it all week and rejoicing in it all day, every Shabbath? We can bring this understanding, this idea, this teaching down to every single mitzwah, but let's start with Shabbath, because on Shabbath we have the freedom from all the distractions of the week to really focus on the unique mitzwah that is Shabbath.