I could not have imaged there would be joy in this. (Para. 3)
Meaning: In the very beginning, I didn't see in my mind or picture that there would be joy in the job.
Please notice the subjunctive mood used in the sentence.
image: vt. make a copy of the form of something; make picture of; see in the mind
Try to image being on the moon. 設想一下在月球上會是怎么個樣子。
Can you image a world without wars and fighting? 你能設想一個沒有戰爭、沒有沖突的世界嗎？
It is hard to image a society without law. 很難設想一個沒有法律的社會會是個什么樣子。
image: n. a copy of object(s); mental picture of an object
I cannot make an image of that old novel in my mind. 這本小說在我腦海里的印象已不深了。
He is the very imag of his father. 他的長相酷似他父親。