Use an old 15" MacBook Pro (early 2008) as monitor for MacBook Pro (2015)?

Hi, I've looked all over forums and numerous instructional websites, but the only solution that seems viable (yet) is software. I'm looking for a hardware- wiring solution to use my old MacBook Pro as a display monitor. I have an HDMI port and 2 Thunderbolt output ports on my new MacBook, but my old one only has VGA (output), Firewire 400, and Firewire 800. I know there are multitudes of adapters across the universe, but what I'm wondering is:

• if I even can use cables to hook up my old MacBook Pro as a monitor
• how to do so, what cables (and what programs if needbe)

Please note: Neither computer is a desktop iMac, and the less software required the better. I am open to software solutions if the argument for them strongly outweighs the practicality and simplicity of a wire.