One of the most terrifying notions is amnesia – not being able to remember who you are or anything about your life. Just ordinary forgetfulness is bad enough, but amnesia just takes that unsureness to a much higher level. And, while we may want to forget aspects of our past, no one wants be totally devoid of all remembrance of their past.
Isaiah is asking the people of Israel if they have amnesia – have they forgotten who reigns in heaven, who created all that surrounds them, who watches over the Israelites and planted them on the land they inhabit? We, also, share in that amnesia, forgetting who is in charge, who brings in the harvest from the seeds we have planted.