I wish people would focus on the "process" of perfection and stop talking about the "condition" of perfection.
Based on the original meaning in Matthew, I wish "Be ye therefore perfect" was translated in our own modern vernacular as, "Become ye therefore perfected." I like "become perfected" much more than "be perfect" - since it doesn't carry the same mis-perceptions about being mistake-free in the here and now.
Envision a sculptor laboring for years over his "masterpiece" - perfecting it carefully, smoothing over flaws in the initial creative process, altering it by chipping away the rough edges or redoing the blurred and faded colors. Such a product wouldn't be "imperfect" due to "mistakes"; it would be imperfect simply because it is not completed / finished / wholly developed - because there still is work to do and changes to make until it is what its creator meant it to be when he first started molding the original lump of clay. Any marring caused by exposure to the wind or rain or hardness of the material itself would be "fixed" by extra attention and detail and softening of the material itself - making it more malleable in the hands of the sculptor.
How do we become perfected by our own Master Sculptor? First and foremost, by trusting that sculptor to never stop sculpting - to grasp that hope and never let go; next by striving to recognize flaws (areas in need of alteration) - and turning those defects toward Him, to receive His attention and the needed alterations; third, by becoming softer and more malleable - more able to internalize the characteristics of perfection (those articulated in the Beatitudes and the rest of the Sermon on the Mount) that ALL denote a degree of softness and openness rather than "a hardening of resolve". This process can be seen as coming alive in the hands of the sculptor - consciously choosing to reduce our natural rigidity and allow ourselves to be molded into what He envisioned when He condescended to create us as His children.
With this vision, we could stop beating ourselves up over things in our past that we simply cannot change and focus on identifying those flaws that caused the pain of our past. We could stop trying to fix ourselves through the sheer force of our will and focus on following His blueprint for spiritual growth that will fix our flaws. We could develop a softer heart to accept and internalize His will for us, rather than develop a harder resolve to do what we think we should do.
It truly is one of mortality's greatest ironies that babies and young children often heal much more quickly and suffer far less serious injury than adults, and it is related directly to their lack of rigidity and being less hardened and "set" in their condition. Children change constantly, but those closest to them - who see them every day - often see those changes less clearly than those who only see the children every month or year. Perhaps being as little children means more than just being open to vocal correction - as it often is perceived. Perhaps it means being open to "alteration" and "growth" - being more malleable and able and willing to be molded and changed - to continue to grow and become something different every day and week and month and year. Perhaps it means being willing to accept the slow and incremental growth inherent in the process of alteration (the possible), rather than demanding a condition before it is complete and being frustrated with the inability to achieve the impossible.
Please, think of this difference (an on-going process vs. a mistake-free condition) before you use the word "perfect" in a spiritual sense.